The Tenth Planet Shrinks Under Hubble's Gaze

starexplorer2001 writes "An object called the 10th planet by some astronomers is not as large as previously thought. New images of 2003 UB313 (aka Xena) were delivered by the Hubble Telescope and showed up as only 1.5 pixels! Now, some are calling to demote Pluto and kill Xena."

Comments

Planet?

[Misch]

Is it a planet or a pla-not?

Blast!

[bl4nk]

This has to be another sinister plot by Aries! Xena should have killed him when she had the chance!

Re:Blast!

[Skreems]

She did, but he came back as Ares

Re:Blast!

[Anonymous Coward]

Next time, will he come as Ars?

Re:Blast!

[Anonymous Coward]

Ares? Ares doesn't exist, I tell you! Thats all a bunch of propaganda spread around by those barbarous Greeks! Oh, God of War you say? The real God of War is Mars, and he's Roman! And no, we didn't steal him from the Greeks. Listen, if the Greek gods really existed we would have named the planets after them or something... But we didn't, so there!

Re:Blast!

[Anonymous Coward]

I'd heard that you lose control of your vowels when you die, but I'd never seen it in action before.

atomic?

[caffeinemessiah]

how exactly do you represent or see half a pixel? i thought pixels were supposed to be atomic...?

Re:atomic?

[staticdaze]

This is off the top of my head, but I would think they could determine that "half pixel" based on the shade of the entire pixel relative to the "main" pixel that actually contains most of the body. If it's 75% darker, assume the object extends 25% into that pixel? Am I close?

Re:atomic?

[Detritus]

Intensity.

Re:atomic?

[helioquake]

A pixel is small, but nowhere near subatomic. It's measured only in microns.

When photons are distributed over the CCD surfrace, it has some measureable shape (e.g., Gaussian) which can be fitted as such to characterize the shape. The quoted size of 1.5 pixel is, I think, the FWHM of the fitted Gaussian function that characterize its source.

Re:atomic?

[Anonymous Coward]

atomic

adj. [from Gk. `atomos', indivisible] 1. Indivisible;
cannot be split up.

He wasn't talking about atoms...

Re:atomic?

[Anonymous Coward]

Your first sentence makes no sense. On a camera a pixel represents an *angle*, not a length. If you know where the object is then the pixel can become a length. In this case 1 pixel = 1000 miles. Not microns.

Re:atomic?

[Vellmont]

A pixel is small, but nowhere near subatomic. It's measured only in microns


By atomic, the author means it cannot be divided further. This was the original meaning of atom. Atomic is a word used in computer science to indicate an operation that can't be interrupted. It either happens completely, or doesn't happen at all.

Re:atomic?

[binarybum]

maybe, but this still seems bizarre - why not map the pixels into real space and give a value based on a non-discreet scale (like meters or football fields)?

Re:atomic?

[Black Copter Control]

how exactly do you represent or see half a pixel?

Think of it as the inverse of anti-aliasing.

Re:atomic?

[helioquake]

I'm talking about the physical size of a pixel on the ACS/HRC.

Re:atomic?

[hazem]

Libraries of Congress? It's one of my favorite units.

Re:atomic?

[gameforge]

You guys are making this too complicated. NASA's site says: "Located 10 billion miles away, but with a diameter that is a little more than half the width of the United States, Xena is only 1.5 picture elements across in Hubble's Advanced Camera for Surveys' view."

Think projection in a 3D game. A pixel represents, at a projected distance of 10 billion miles, a width x. Xena is 1.5x.

The final image (as you all have pointed out) would require a minimum of two pixels of information to accurately reproduce the projected image from a distance of 10 billion miles. The second pixel would not have the intensity of the first. But from the image on the site, it looks like a lot more than two pixels of information were recorded; I don't see how they could magnify two pixels and get that.

Re:atomic?

[Carewolf]

Which does not fit this case because a pixel can have many colors, by which you can estimate how much of the source is providing light to the pixel.

Re:atomic?

[StarkRG]

Hey, as long as we're applying units to measurements of a different type why not measure it in feet/sec, or perhaps in watts? volts? degrees kelvin? how about in hours?

It's five hours big.

Re:atomic?

[Oink]

This is true, but I think the question was aimed towards how they supposedly can divide a pixel since it's supposedly the smallest thing they can resolve. I actually worked on a cosmology project for a couple years, so I have at least a rudementary understanding of image capturing techniques. You can overcome the limitations of your CCD through a technique called dithering. The standard dither is 2x2, in which you take an image, move your image to the right by half a pixel, down by half a pixel, left by half a pixel, taking an image at each of these points. Now you can sort of average out these images and can actually resolve things that are smaller than a pixel.

There's a paper somewhere that claims that a 2x2 dither can also eliminate the effects from any 'reasonable' intrapixel variation. That is, if for example the edges of your pixels are slightly less sensitive than the centers, which is actually quite common. This makes dithering an extremely valuable technique in wide surveys where the characteristic size of an object in the sky is less than the size of a pixel. This is called undersampling. I could say more, but I think that answers the question. ;)

Re:atomic?

[Shimbo]

how exactly do you represent or see half a pixel? i thought pixels were supposed to be atomic...?

Antialiasing.

Re:atomic?

[Lord Kano]

Interpolation?

I would imagine that they determine 1.5 pixels by measuring its effect on nearby pixels.

LK

Re:atomic?

[tomcres]

Oh, they must be using sub-pixel rendering, like ClearType! :)

Re:atomic?

[Anonymous Coward]

And the OP was not. Understand now?

Re:atomic?

[Anonymous Coward]

Which doesn't change the fact that the previous poster completely misunderstood the question that the OP was asking, prompting the response by the parent of your post.

Re:atomic?

[Chapter80]

Libraries of Congress? It's one of my favorite units.

My thought exactly!

While we're discussing this, if all the book stacks in the Library of Congress were replaced with digital media containing the contents of the book stacks, how many Library of Congresses would it hold?

Re:atomic?

[justthinkit]

And how big a pipe would you need to share it with the world?

Re:atomic?

[compwizrd]

And I can cross that in 12 parsecs.

Re:atomic?

[necro81]

The pixel size is a measure of the apparent diameter of the object in space. A sphere way the heck out there appears as a zero-dimensional dot to us. With some magnification, planets will appear as small discs. An astronomer will usually measure the size of that disc as an arclength, how many degrees, minutes, or seconds the disc spans across the whole the night sky. If the astronomer also knows the distance to the object, they can figure the diameter of the object in terms of distance (miles, kilometers, etc.).

The CCD camera that Hubble used for these images has a certain physical size (length, width), a corresponding pixel size (for an example: 1024 pixels across by 1024 pixels tall, a 1 megapixel image), and due to the mirrors and lenses on the telescope, can see a certain area of the sky. That field of view is measured as arclengths, say, 15 degrees wide by 15 degrees tall (again, just an example). So, from simple division, one can correspond a given arclength across the sky to a number of pixels. An arclength of 15 degrees corresponds to a pixel size of 1024 pixels. An object that measures half a degree across (like the disc of the moon) would create an image 0.5/15*1024 = 34.133 pixels wide.

Note that we have just produced an image with fractional pixels. This is no error. Pixels have some physical size, like all electronics. They are not discrete points. Depending on the specific CCD chip, the pixels' physical size could be on the order of 10^-5 or 10^-6 m. Small to you and me, perhaps, but actually quite large in the world of electronics. Imagine a CCD sensor as a sheet of graph paper - each square (not vertex) represents a single pixel. Now draw and fill in a circle on it whose diameter is 34.133 pixels wide. You'll end up with a lot of pixels that are completely filled, but all the ones on the edge are partially filled. These are the "fractional pixels." When the CCD spits out numerical data about the image, those partially filled pixels will be represented in shades of grey.

Re:atomic?

[maxwell demon]

Think of it as the inverse of anti-aliasing.

Aliasing?

Re:atomic?

[Szaman2]

Yes they are atomic (ie not divisible). But that does not mean that you cannot detect presence of objects smaller than a pixel in a photographs. Hell, sometimes it is even worse - you can have an object that is smaller than 1 pixel appearing directly on the border line between 2 pixels. For example let's assume that you put a black dot, on a white canvas and photograph it from a distannce so that in the image it's size is 1 pixel or less.

Let's assume that the center of your dot is on the borderline of pixel 1 and pixel 2. Thus those two pixels are not "pure" white. They are "poluted" by the black dot, but both still contain white. Since you can't subdivide pixels, you need to aproximate the color value to be displayed. Thus the color of the pixel will most likely be a mix of its component colors. In our case, pixel 1 and pixel 2 will probably end up gray-ish.

Now, if you know the consistency of pure white, consistency of pure black, and the scale of your picture (ie. 1 pixel = n square inches) you can calculate the size based on the size and color of the non-pure pixels.

They probably use muli-spectral data for these type of images (ie. data is collected over multiple wavelengths, not just visible light). If you have more bands than just standard RGB you can be even more accurate in measuring these things.

Re:atomic?

[visgoth]

It's five hours big.

I had chinese buffet for lunch. It was 2 hours big!

Hey! You might be onto sonmthing here!

Re:atomic?

[helioquake]

My head is finally clear of medication...

Now I'm re-reading some of my posts...and your post still doesn't make any sense. Are you taking some medicine with control substance, too?

Re:atomic?

[helioquake]

In this particular case, they may have used dithering (or drizzling). I surely would use a 1/2-pixel offset pattern, if I were them.

But to derive the characteristic Gaussian width of 1.5pixel, you don't need to. Because of the PSF at that waveband (435nm) with the HST is about 0.05" (arcseconds), or 2 ACS/HRC pixels. So the apparent size of the source would look like

      sqrt((1.5)^2 + (2.0)^2) = 2.5 pixel wide

And that's fairly large enough to measure its size without a fancy method.

PS. your points are all valid! Not many people knew about the degrading sensitivity near the pixel gap.

Re:atomic?

[McFadden]

>And the OP was not. Understand now?

>>your post still doesn't make any sense

And the [Original Poster] was not [talking about the physical size of a pixel on the ACS/HRC]. Do you understand now [that your original reply misunderstood what he was saying]?

Re:atomic?

[Silver Gryphon]

These are Quantum Pixels.

Between Scott Bakula and Kevin Sorbo, there's got to be a spaceship involved in this whole scandal.

Maybe...

[Anonymous Coward]

Maybe it's all black except for a bright white spot.

Re:Maybe...

[SlowMovingTarget]

EEEEEeeeeeewwwww... A zit so big Hubble could see it...

Looks like

[dawnread]

"Now, some are calling to demote Pluto and kill Xena."

The War on Terrible Planet Names has begun ;).

Xena

[Detritus]

Forget Xena, the planet should be named Marvin.

Re:Xena

[Black Copter Control]

Forget Xena, the planet should be named Marvin.

No. George. It started a war with an inflated estimate.

Re:Xena

[Funkmaster_G]

At least they didn't call it Urectum.

Re:Xena

[Alioth]

A better name would be Rupert.

Re:Xena

[Anonymous Coward]

Fry: "Hey, as long as you don't make me smell Uranus." *laughs*

Leela: "I don't get it."

Professor: "I'm sorry, Fry, but astronomers renamed Uranus in 2620 to end that stupid joke once and for all."

Fry: "Oh. What's it called now?"

Professor: "Urectum."

Re:Xena

[gkhan1]

Acually Uranus was supposed to be called George's Star (only in latin) for King George III, if the discoverer (William Herschel) had had his way.

Re:Xena

[hal2814]

And here I though Mondas was the Tenth Planet. Those sneaky Cybermen.

Re:Xena

[Anonymous Coward]

I know. Hateful, isn't it?

Re:Xena

[maxwell demon]

Or Persephone.

Re:Xena

[LouisZepher]

Either way, it'll muck up my horroscope...

Only 68 miles bigger

[RLiegh]

Xena has only 68 miles on Pluto, but it's mostly made of ICE. One good solar flare up and *poof*, no more Xena.

Re:Only 68 miles bigger

[Bushcat]

*poof*, no more Xena

I'll bear that in mind as the flare passes us en route, with 4900 times the intensity it will have when it reaches Xena. "I bet RLiegh's having a chuckle right now", I'll think to myself.

(4900 assumes Xena is at an average 70 au)

Re:Only 68 miles bigger

[RLiegh]

As George Carlin said pollution; Earth will be fine. We might be fucked; but the earth will be A-OK.

Re:Only 68 miles bigger

[RLiegh]

,s/said pollution/said about pollution/g

Re:Only 68 miles bigger

[TrevorB]

Unless the greenhouse effect is runaway, like Venus, and all the water is evaporated away. Then we're all fucked.

I did some scary back of envelope calculations today about Venus. It's closer to the sun, and receives about 1.9 times the sunlight as Earth. But its atmosphere is so reflective (which is why it's so bright in the sky, the albedo is almost twice that of Earth), that only half the amount of sunlight gets through the CO2 and SO2 clouds without being bounced back into space.

Venus receives less energy from the sun than Earth does.

I try not to think too much about that, it scares the living crap out of me. Something went terribly terribly wrong with Venus. We need to figure out what that was.

It's likely that earth has a corrective measure that will throw the planet back into a severe ice age if CO2 levels rise too high. Our history is dominated by ice ages. Still I like my planet the temperature it is now, not severely hotter or colder.

Re:Only 68 miles bigger

[tomatensaft]

This enormously CO2-rich atmosphere results in a strong greenhouse effect that raises the surface temperature more than 400 C (750 F) with temperatures at the surface reaching extremes as great as 500 C (930 F) in low elevation regions near the planet's equator. This makes Venus's surface hotter than Mercury's, even though Venus is nearly twice as distant from the Sun and only receives 25% of the solar irradiance (2613.9 W/m in the upper atmosphere, and just 1071.1 W/m at the surface).

From: http://en.wikipedia.org/wiki/Venus_(planet) It is believed, that surface temperature doesn't get much lower even in Venus' night-time, even though day cicle on Venus is very-very long... :) (116.75 Earth days actually)

Re:Only 68 miles bigger

[StarkRG]

If you really want to scare the pants off you and the shit outta you (preferably in that order, otherwise you'll have to change) read Bill Bryson's "A breif history of just about everything."

In it he explains how much of an anomoly we are, not only that life appeared on this planet, not only that it evolved to multicellular organisms, not only that it evolved into inteligent beings, but also that it survived all the many catastrophes that might have occurred throught that process, and how, at any minute, any number of things could completely wipe us off the planet.

He talks about how as greenhouse gasses build up in the atmosphere one of a couple things could happen, either the heat is trapped on the surface and continues to build rapidly, boiling the seas and creating more greenhouse gasses (a neverending cycle, it'd never end without some outside influence), or the gasses would reflect the heat from the sun causing the climate to initially heat up (shrinking the ice caps, and causing more evaporation) and then (relatively) suddenly getting very cold, creating more and more ice, which reflect more and more sunlight.

We're really kind of walking along a tightrope when it comes to this kinda thing, and we're dancing around mindlessly with a bowling ball in our hand, it's a total fluke that we havn't fallen yet.

Oh, and we're technically still in an ice age just at a short high point in temperature, normally the tempareature is either freezing cold (ice covering most of the planet) or swealtering hot (tropical just about everywhere), mostly freezing cold though...

and that's just the temperature, I didn't get into the potential extraterrestrial bombardment (now that doesn't mean aliens, it just means things not from Earth), supervolcanos (Yellowstone), disease, etc. Not to mention things that we've done, are doing, and may continue to do, to ourselves.

I highly reccomend Bill Bryson's book, it tells you we're doomed in a way that'll keep you laughing the entire time.

Re:Only 68 miles bigger

[Zaatxe]

And also *poof* us, since we are in the way and much, much closer...

Re:Only 68 miles bigger

[Improv]

Sure, and if you stab someone, they'll be ok. Oh, sure their life processes might stop and they might cease to be recognisable for the attributes we value about them, but their bones and stuff will be around for quite some time.

Re:Only 68 miles bigger

[maxwell demon]

I guess a solar flare large enough to melt ice at 97 AU (distance Sun-Xena) would probably melt stone at 1 AU (our distance to sun). Or more likely, evaporate it. So *poof*, no more Earth as well.

Re:Only 68 miles bigger

[WhiplashII]

Whenever I read about doomsday scenarios like that, I remember several things:

1) We are not the biggest thing to hit Earth - Go back 100 million years, see what is the worst that happened. That did not kill all life, that did not boil off the ocean (in fact, Earth has never been above temperate ever since life began. We should be worried about the cooling that happens all the time, not the warming which has only ever made our planet a paradise!)

2) Humans survived the last ice age. In tents. Without electricity.

Re:Only 68 miles bigger

[Citizen of Earth]

Still I like my planet the temperature it is now, not severely hotter or colder.

Being a resident of inland Canada, I ask the global community to keep polluting! Milder winters, earlier spring, it's not so bad.

Re:Only 68 miles bigger

[Grishnakh]

2) Humans survived the last ice age. In tents. Without electricity.

Yeah, but those humans weren't the total wusses we are now.

Now, we've built up complex, interconnected societies on a global scale. The only way all 6.5 billion of us are able to survive is because of these complex societies which provide us food, shelter, sanitation, etc. There's simply too many of us to go back to being hunter-gatherers. Any severe climatic disaster would probably disrupt our societies, and cause massive chaos resulting in starvation and warfare. Most of the population would probably be killed before things stabilized again.

Yes, some humans will probably survive, but most of us won't. And those who do will probably be living in stone-age conditions.

Re:Only 68 miles bigger

[LouisZepher]

But as everyone around you is evaporating into whiffs of hydrogen, ozone and carbon monoxide, you'll be too busy evaporating yourself to care...

Re:Only 68 miles bigger

[Anonymous Coward]

The British House of Lords actually said a similar thing: "The House of Lords report even suggested we might not be worse off with warming, on the whole, given how much better plants will grow."

Re:Only 68 miles bigger

[geekoid]

Actually, if the earth is in the way of that flare, it's fucked to.

Sure, it will still be a ball of rock, but there will be no life, at all.

Re:Only 68 miles bigger

[WhiplashII]

Ok, this is a plausible scenario. But let me ask you - if you knew that over the next 10 years the earth was going to get so cold that crops wouldn't grow (probably the limitting factor), how much would you (personally) be willing to spend to make sure that you were on the team that still had food? This is probably approximately equal to your net worth. Taking just the net worth of middle class Americans (assuming the rich are totally uncaring and the the poor have absolutely nothing), that would be about $10 Trillion.

Now let's suppose that I have a cunning plan to feed all those middle class people, but that it is totally impractical - such as building a large space station for farming (hey, getting stuff down from orbit is cheap!) - and let's further suppose that there are no cheaper alternatives. Would I be willing to build said station for $10 Trillion?

Of course what really happens is that farmers start farming the oceans, etc for far less money. Food skyrockets to 20 times it's current price, but fewer people actually starve because since there is more money in farming (and you can now only farm in the tropics) farming is run more like a business and distribution is more efficient. And you know that the democrats are not going to let people starve - well the same is true of other countries. (If you look at the starving people it is not due to lack of food, it is due to lack of distrbution of existing food.)

Really, these scary scenarios are not realistic at all. We are here to stay as long as we are not hit by a cosmological event or a nuclear war with Iran. (Even then, half the population survives).

Re:Only 68 miles bigger

[maxwell demon]

Unless I should find out that my friend in reality comes from space and researches for the next edition of an electronic book which has the words "don't panic" written on it in large, friendly letters ...

Re:Only 68 miles bigger

[StarkRG]

He actually discusses this in his book as well. No, they didn't destroy all life on Earth, but they almost did. Apparently every human alive today is descended from a group of about 100 individuals, the sole survivors of an ice age or something like that.

Even if 2000 people out of 6.5 mil survived I think everyone would agree that's a pretty big disaster, especially to those of us who wouldn't survive...

Re:Only 68 miles bigger

[StarkRG]

Really, these scary scenarios are not realistic at all.

Hoo boy, you are quite the optomist...

They are quite realistic, and actually very probable. Besides, in all likelyhood we're not going to have much notice before it happens. And even if we did, have you ever noticed how people bitch and moan when ten or fifteen people die in one day during a heatwave? Imagine what would happen if a couple billion did... that's less than half the worlds population.

Re:Only 68 miles bigger

[StarkRG]

oh, and, no, we're not the biggest thing to hit the planet, but we are the most persistant. (And I believe the only single species to outnumber us in the history of the planet would probably be insects, bacteria and some smaller plants.

Re:Only 68 miles bigger

[WhiplashII]

I'm curious - what do you consider a realistic timeline for conversion from the current Earth to an ice age Earth?

Personally, I believe we could get most of Earth's population off planet in about 20 years if we had to.

But then, that's what I'm working on - so I know what could be done with a couple $100B... I'm sure there would always be better alternatives.

Re:Only 68 miles bigger

[WhiplashII]

Um, I was actually referring to large crater making devices, volcanoes, comets, the natural nuclear reactor of Africa, the fire that pretty much covered the globe, etc.

Re:Only 68 miles bigger

[RsG]

To point out the bleedingly obvious, Venus's surface pressure is several orders of magnitude greater than ours. Even if there were no greenhouse effect there, it would still be much, much hotter (remember, there is a direct relationship between pressure and temperature).

There is no way for Earth to reach venusian atmospheric density, and no way that Venus ever had something remotely resembling terrestrial temperature/pressure. It isn't just a matter of what proportion of the air is Co2, it's a matter of how much air there is in an absolute sense as well.

Re:Only 68 miles bigger

[TekGoNos]

I'm curious - what do you consider a realistic timeline for conversion from the current Earth to an ice age Earth?

Three years!

Yes, I'm serious :

Looking at the ice cores, however, scientists were shocked to discover that the transitions from ice age-like weather to contemporary-type weather usually took only two or three years. Something was flipping the weather of the planet back and forth with a rapidity that was startling.
(Ok, this is the reverse direction : Ice Age -> Normal)

What brought on this sudden "disappearance of summer" period was that the warm-water currents of the Great Conveyor Belt had shut down. Once the Gulf Stream was no longer flowing, it only took a year or three for the last of the residual heat held in the North Atlantic Ocean to dissipate into the air over Europe, and then there was no more warmth to moderate the northern latitudes. When the summer stopped in the north, the rains stopped around the equator: At the same time Europe was plunged into an Ice Age, the Middle East and Africa were ravaged by drought and wind-driven firestorms.
(This is about Normal -> Ice Age)

Source

So, IF we get an Ice Age, it could come REALLY fast.

Re:Only 68 miles bigger

[WhiplashII]

Ok... three years... hmm...

I think you need to look more cirtically at the site that you quote. Note that they make broad statements of fact, such as "Great Conveyor Belt shut down", without presenting any evidence of that. So they present an idea (the Great Conveyor Belt is the key to warm weather), then they tell a story (30,000 years ago it got very cold) and say QED, the idea is true. This is a very common approach to false science, essentailly an emotional play rather than a rational play.

How do they know that the Great Conveyor Belt shut down? What is the evidence? (Note that I am not claiming that they have no evidence, merely that they do not ever present any evidence).

OK, some basic engineering - the water on Earth masses about 1.4e21 kg. For the most part, it is near room temperature. So let's say that humanity will not survive a 10C change (I would say that we would, but that is a different issue). OK, so the Earth needs to lose 10C * 1.4e21 kg * 4 kJ/kg, about 6e25 J of energy.

For comparison, the sun provides about 350 J/s to each of the 5e14 square meters of Earth, for about 2e17 J/s. So (assuming that the Earth is currently near energy balance, which is probably a good assumption) if the sun goes out completely, we have 3e8 seconds (about 10 years) before we lose 10C in temperature. For your scenario to be plausible, the Earth has to be losing energy 3 times faster than the sun is currently adding it - in other words the Earth would be glowing in the visible (or at least near visible) spectrum. (Assuming the Earth is losing energy via blackbody, which is the worst case, the temperature of the Earth would need to be 1.4 times the current temperature in Kelvin - about 500 K = 200 C)

This was a very simple analysis, glossing over many issues - but 3 years to an ice age is simply not a possibility. At the very worst case, the climate may change and force us humans to live somewhere else (the ocean, for example) - but the end of humanity is not on the radar.

Re:Only 68 miles bigger

[TrevorB]

Yes, but why? I've seen discussion that suggests that a lot of that atmospheric CO2 is locked up in carbonate rocks on Earth. I'm uncertain if the levels are comparable.

Venus and Earth likely were practically identical at one point, moving at similar but subtly different evolutionary paths. What was the difference?

Re:Only 68 miles bigger

[RsG]

The explanation I always heard was that the differece was the event that formed the earth's moon.

It's theorized that another plaentary body collided with earth early in our solar system's history. This collision resulted in the ejection of a debris field, which would eventually form the moon, and the blasting away of most of the atmosphere. Additionally, it's possible that the presense of a moon either further reduced the atmosphere, or prevented it from reaching it's previous density (ie, gasses in the upper atmosphere would be pulled away by tidal forces).

Under this theory, venus is normal for a rocky planet of it's size, and earth has an unusually thin atmosphere.

"...not as large as previously thought."

[core plexus]

"I swear it's a foot long, it just shrank because of the cold of space!" --

New Face discovered on Mars

Re: "...not as large as previously thought."

[frankie]

Hey, you'd have "shrinkage" too if you were covered with shiny methane ice!

p.s. Galle Crater / Argyre Planitia is not "new" by any definition. It was seen by Viking in 1976 ... and it formed some million years ago.

A planet by any other name....

[svunt]

Ah, I still remember fondly the first time I saw a slashdot thread climb to a few hundred posts of argument about 'what makes a planet a planet?'. If ever a term was crying out for a rigid, ostensive definition from astronomers, it's 'planet'. From the ancient greek word for "wanderer", if we don't tighten it up some, the argument will come trotting out every time someone finds a rock doing laps about the sun. Stays within 10 degrees of the ecliptic, say 3,000km across...that works for me.

Re:A planet by any other name....

[inhalentbroom]

I agree. Personally, I think we should just nuke Xena so that the planet debate doesn't come up.

Re:A planet by any other name....

[tqft]

Why within 10deg of the ecliptic?

Historical property known "planets"?

If we found an earth sized object but at 90 deg to ecliptic would you change your definition? At a Pluto like distance it could be out there - too dark and small to detect.

Re:A planet by any other name....

[Godwin O'Hitler]

You can bet your life that somewhere out there there's a previously undiscovered body measuring 2,999km just waiting for the day your definition gets official acceptance.

Re:A planet by any other name....

[qazsedcft]

I agree with the other guy. The angle to the ecliptic shouldn't matter. I think we don't know enough to define "planet". What if other stars have different kinds of planets that we don't even know of. Until we learn more about extrasolar planets I think a good working definition could be something like "approximately round shaped body, diameter at least 1000 km, orbiting a star". Yes, that would include Pluto, Xena, and a bunch of others. We can have a very broad definition first and then refine it with terms such as "minor", "terrestrial", "giant", and so forth. Frankly who cares if textbooks have to be changed? Kids in school should learn that there are some minor planets out there even if they don't learn them all.

Re:A planet by any other name....

[gameforge]

> If we found an earth sized object but at 90 deg to ecliptic would you change your definition? At a Pluto like distance it could be out there - too dark and small to detect.

I'm pretty sure we'd see it, unless it were all black, or something prevented it from reflecting light.

I do agree though, the definition of a 'planet' should work for all uni-star solar systems, and being that Earth does not exist simultaneously in every solar system, making the definition of 'planet' relative to Earth doesn't make sense.

I personally would classify an object with any orbit (and thus Pluto, Xena, etc.) to be a planet. If we really incist on saying that it should be a circular orbit, that's about as precise as you can get, although I don't like that either... as I said in another reply, even our own familiar "planets" are so different from each other that I think a "planet" should either have a very broad definition (e.g. any gravitationally significant object orbiting a sun for a living) or refer to our 8 planets that have been in the telescopes of astronomers for centuries, I guess for historical purposes/kids sake. In essence, a meteor that closely resembles a planet but has a noticeably elliptical orbit at a funny angle should still be a planet and studied as such; along that same line of reasoning, each of our eight planets should be studied with a very "open mind" (e.g. they're all a hell of a lot different from each other, originated via different processes, etc.).

Re:A planet by any other name....

[tqft]

"I'm pretty sure we'd see it, unless it were all black"
you are probably right there - drop it back to 2 * pluto avg distance and seeing it would be a dodgy proposition

"If we really incist on saying that it should be a circular orbit,"
http://www.solarviews.com/eng/solarsys.htm
Down the bottom of the page - eccentricity = 0 for a circular orbit so even that doesn't work - Pluto and Mercury would well and truly fail at >3 * average ecc of those planets in that table including themselves.

Re:A planet by any other name....

[MrMr]

If ever a term was crying out for a rigid, ostensive definition from astronomers, it's 'planet'

You must be a lawyer. Or perhaps you were just brainwashed by the patent department.

I suggest that, rather than founding an interplanetary comission (so the Xenians may or may not be in it) for the ultimate definition of planethood, we learn to live with a universe that has a number various sized lumps of matter in it, and use language to explain more precisely what we mean in a particular case should the need arise.

Re:A planet by any other name....

[gameforge]

True about the Mercury and Pluto. It's a very important distinction, because a planet that's 2 Au from the sun for part of the year and 25 Au for another part is going to be a very different place than a planet that's the same distance year around. Certainly Mercury and Pluto aren't that extreme... but they're still porbably different in some way for it. But the other 7 planets with circular orbits on relatively the same orbit plane (+/- a couple degrees right?) are vastly different from one another in their own right... orbit shape or incline is really just one more characterstic that makes a "planet" unique.

Re:A planet by any other name....

[squoozer]

Personally I always thought the best definition of a planet would be a body with enough mass to pull itself into roughly a sphere. That would discount pluto for now at least. The actual mass doesn't need to be accurately defined - if it's round it's a planet. I don't think we even need to specify that it must orbit a star. If it doesn't have enough mass to pull itself round then it's just a big lump of rock.

Re:A planet by any other name....

[rcamera]

by your definition, the sun is a planet. wouldn't that make earth a moon?

Re:A planet by any other name....

[pla]

Why within 10deg of the ecliptic?

Because he wanted to limit our definition of "planet" to basically refer to sufficiently-large objects that formed from the same accretion disk as the Earth, and have a reasonably-stable basically-circular orbit (for which reason I'd also suggest including a criterion for orbital eccentricity, so if we ever find a comet or similar kuiper object asteroid the size of Neptune that just happens to travel perfectly along the ecliptic, we don't get into this same stupid debate all over again).

Pluto, with its highly inclined orbit (up to 17deg from the ecliptic - The next worst, Mercury, only makes it 7deg) quite possibly did not originate from our solar system's accretion disk.

Re:A planet by any other name....

[Anonymous Coward]

'George - yes, there's peaceful Iranian nuclear facilities on this dismal ball at the edge of the solar system - what ? We can launch as soon as we're ready ? Thanks George, the people of the free world are lucky to have you as a leader.'

Re:A planet by any other name....

[Anonymous Coward]

Planets are not a ball of fire consumed by nuclear activity while emitting light either. Some things are just understood. Some people just aren't; like you for instance!

Re:A planet by any other name....

[Anonymous Coward]

Thanks. Beat me to the taunting.

Re:A planet by any other name....

[GoRK]

According to Saturday Night Live, not only is the sun a planet, it's also Harry Caray's favorite planet.

Re:A planet by any other name....

[argStyopa]

A good comment by the discoverer of Sedna, Xena, etc, to the effect that the term "planet" is probably best used like "continent" - it doesn't really have a rigorous scientific definition but every pretty much agrees what it applies to.

Re:A planet by any other name....

[Anonymous Coward]

A fixed maxiumum inclination is just as arbitrary as a fixed minimum size. Also, simulations indicate that almost all Kuiper Belt objects probably formed in the accretion disk, but the ones not in low-inclination orbits were tossed into thier high-inclination, elliptical orbits by encounters with more massive planets (Neptune and the like). Before you try to use the previous sentence to argue against Kuiper-Belt-Planets, it should be noted that many large extrasolar planets have odd (highly elliptical) orbits, and simulations have shown that planet interactions can toss even jovian-size planets into strange orbits.

Re:A planet by any other name....

[Anonymous Coward]

Pluto *is* spherical. So is Xena, Sedna, Quaoar, Orcus, Ceres, and at least 19 moons of the Outer Planets. In fact, I've heard your definition argued against on the grounds that we would end up with *too many* planets (at least 20, even when you discount the moons).

Re:A planet by any other name....

[SamSim]

I'm gonna go for "As big as or bigger than Pluto; not undergoing internal fusion".

Re:A planet by any other name....

[qazsedcft]

I don't understand why this is a problem. We don't complain that there are too many chemical elements or animal species, yet too many planets is somehow a bad thing. Astronomers don't have a problem with Jupiter having dozens of moons, but the Sun can only have a handful of planets. Yeah, the world is much more complicated than we previously thought. It happened many times in the history of science. Just live with it!

misunderstanding?

[interactive_civilian]

I think the GPP meant atomic as in "smallest reduceable unit", which came from the Greek atomos which means "indivisible".

So, how do you get half a pixel on a screen? I too was under the impression that an individual pixel was either all on or all off...

Re:misunderstanding?

[Anonymous Coward]

there exists a data aquisition and processing technique called drizzling. it is quite sophisticated but in short consists of taking serveral just slightly displaced and rotated images of the interesting object. then you subdivide each pixel on the images into smaller bits and overlay all the images on a new subpixel grid. but how this holds with the nyquist critera that requires two pixel to be exposed to clearly say that a feature on the picture is there or not, i do not know...

Re:misunderstanding?

[helioquake]

So, how do you get half a pixel on a screen? I too was under the impression that an individual pixel was either all on or all off...

Do you guys know the concept of "resizing a ditital image"?

Subsampling of a pixel can be done by knowing the intensity values in the neighboring 8 pixels (or greater). In other words, you can derive the intensity value at the pixel boundary by taking the mean value of the intensity values detected in these two pixels.

In this case, the measured size is derived based on mathematical characterization of the apparent point source.

I ought to be able to say this in a simpler term, damn it...

Re:misunderstanding?

[Jamu]

The pixels in the article aren't binary atoms though and probably have at least two bits of precision: explaining the claim of 1.5 pixels. More generally, most monitors have three different elements for red, green and blue. TrueType, for example, uses these as the atoms rather than the whole pixel, to get smoother screen text. Modern video cards, when using 3D graphics, can sample more than one point for the same pixel. For example, 4X Anti-aliasing can use up to four sample points per pixel.

Re:misunderstanding?

[Digital Vomit]

Do you guys know the concept of "resizing a ditital image"?

No. Does it have something to do with enlarging a thumbnail image of breasts?

Just click on it instead, buddy. Chances are it goes to a full size picture.

Re:misunderstanding?

[Bemopolis]

More likely, they used a technique called oversampling -- where several images of the object are taken, wit the object centered on slightly different portions of the CCD camera. Each pixel is then subsampled (prob broken into a 2x2 square), the collection of images are shifted so that they are aligned, and added together.

This is probably why they claim it's 1.5 px; what they mean is more than 1 and less than 2, rather than 1.5 vs 1.4 or 1.6.

Oh shit, I just used my degree for something.

Bemopolis

Re:misunderstanding?

[Anonymous Coward]

Oh shit, I just used my degree for something.

Congratulations, you win! :-)

what scale?

[alphakappa]

"New images of 2003 UB313 (aka Xena) were delivered by the Hubble Telescope and showed up as only 1.5 pixels! "

1.5 pixels on what scale? A pixel is not a unit of measurement for size, it just denotes the smallest distinct unit in a picture. Yes, it appears sensational to say that a 'planet' appeared to be 1.5 pixels (100 exclamation marks), but that's just as stupid as saying that my backyard appears to be 5 pixels wide on Google Earth. Gives no information unless you say that the resolution is 1 pixel = X metres.

Re:what scale?

[Anonymous Coward]

that's just as stupid as saying that my backyard appears to be 5 pixels wide on Google Earth. Gives no information unless you say that the resolution is 1 pixel = X metres.

It doesn't tell us your backward's length, but it tells us how close Google Earth is from not being able to resolve your backward, which IS information.

Re:what scale?

[helioquake]

See my earlier post below:

http://science.slashdot.org/comments.pl?sid=182840 &threshold=0&commentsort=0&mode=thread&pid=1511178 2#15111848

Re:what scale?

[TrevorB]

It also doesn't make clear that 2003 UB313 is still larger than Pluto after the new measurement (~1,430 vs ~1,490 miles diameter respectively).

Re:what scale?

[mwvdlee]

The number is just there to give an indication of a possible error margin. At 5 pixels, the size your backyard could be determined well within a 20% error margin. Depending on whether you can differentiate between the surrounding backyards and what the accuracy of measured light is, 5 pixels doesn't say shit about the size of your backyard, but it says a lot about the error margin by which the size of it was calculated using those pixels.

Re:what scale?

[maxume]

It is possible to infer that the planet is almost too small for Hubble to detect. I agree it isn't enough information, but if someone happened to know the resolution of Hubble, they'd have it licked.

Re:what scale?

[Citizen of Earth]

Yes, it appears sensational to say that a 'planet' appeared to be 1.5 pixels (100 exclamation marks)

Take a pill. Scientists are probably familiar with the parameters of the hubble telescope and the details of translating between pixels and angles and meters at a distance are probably irrelevant to the subject the article.

Re:what scale?

[uniqueUser]

A pixel is not a unit of measurement for size, it just denotes the smallest distinct unit in a picture

By this, a pixel can not be the smallest distinct unit in a picture, the smallest unit must be either 1.5 pixels or 0.5 pixels.

Re:what scale?

[penguin-collective]

What they are saying with the "1.5 pixel statement" is not that the thing is small, it is that they can't estimate the size of the object by measuring its diameter (because for that, they'd need more than 1.5 pixels), but they have to estimate it from its brightness. It's a perfectly reasonable thing to say in this kind of article.

hobble in space

[sumdumass]

I guess this is sort of an argument to keep the hubble going. I wonder how dificult it would be to send a robotic mission that not only lifts the orbit but actualy send the hubble into space to orbit the sun outside our own planets gravity. I guess this would let it get closer to objects as well as extend it mission criteria. It probalby could have some sort of comunications relay on the bosters that would relay the hubbles regular comunications on a faster more reliable (for the conditions)system.

I'm wondering exaclty how different the images could be if they weren't effect by earths gravity or if the hubble was actualy closer. Maybe not wiote as far out a pluto but closer too it? Then again it might be cheaper to just build a new telescope and launch it.

Re:hobble in space

[helioquake]

I wonder how dificult it

Your idea would cost more than servicing the Hubble with a shuttle. Actually it might be cheaper to build another one, I'm afraid.

But fear not. The Hubble will be serviced, more than likely, and continue to be operated until a replacement (of sort) becomes available (i.e., JWST, though it ain't nothing like the HST).

Re:hobble in space

[Anonymous Coward]

No, the best thing would be for us to get out into space and build a big-ass telescope on the dark side of the moon. You can achieve a much bigger telescope this way and have infinitely less light pollution problems and whatnot.

Obviously there are a few technical hurdles here, though.

Re:hobble in space

[ChrisMaple]

"The dark side of the moon"

The only dark side of the moon is the inside, and that's not very good for astronomy.

A crater near the lunar axis might have the advantage of always being in shade, but until the moon is populated it's more practical to have a telescope in earth orbit. It's easier to service there.

Re:hobble in space

[odyaws]

I wonder how dificult it would be to send a robotic mission that not only lifts the orbit but actualy send the hubble into space to orbit the sun outside our own planets gravity.

There are lots of considerations that make this infeasible, aside from the pure challenge of a robotic mission of this complexity. A big one is that Hubble is in Low Earth Orbit (LEO), at an altitude of roughly 600 km. This means that one side of it is facing a nice, warm Earth, which helps to keep the temperatures on board in a comfortable range. If you now move the thing out to solar orbit (no small feat), it would be facing cold dark space on all sides. I'm sure it doesn't have the power collection and heating capability to deal with the ensuing temperature drop.

I'm wondering exaclty how different the images could be if they weren't effect by earths gravity or if the hubble was actualy closer.

Um, not different at all. The Earth's gravity has no effect on the images Hubble collects (at least at anything near the scale resolvable by the telescope). Same story with distance - most of what Hubble looks at is so exceedingly far away that Hubble could be at Pluto without making any noticable difference.

Light reflected from Earth could be a minor problem, but I think in the visible spectrum this isn't significant either. For an IR telescope like Spitzer it's important to get away from Earth to get decent images, so they put it in a heliocentric orbit similar to Earth's.

Re:hobble in space

[SnarfQuest]

Don't forget to replace the radio while you are at it. I doubt that the one currently in the Hubble is designed to talk to anything except specific communication satelites.

Re:hobble in space

[Antony T Curtis]

It may probably make more sense to send Hubble into Luna orbit rather than into free space... Less energy and easy to locate and has one BIG bonus: when its on the far side, the Moon is acting as a giant shield against all the crap that Earth emits.

Hmm... How about a Luna-orbit radio telescope?

Re:hobble in space

[thePig]

The space , even inside the solar system, is so huge, that you idea has no merit.

Re:hobble in space

[nasch]

Wouldn't the sun hit Hubble with a great deal more heat than the Earth? Put it in deep space, and now it's never in the Earth's shadow so it would get hotter. I don't see how being close to Earth, but not in its atmosphere, keeps Hubble warm.

Size

[aepervius]

It is nice to know that it is only 1/2 pixel or whatever number of pixel, but how about a real size ? in kilometers ?

Re:Size

[helioquake]

It can be derived with trigonometry:

    (angle)*distance_to_the_object == size_of_the_planet

which are

    (1.5pixel*0.025"/pixel)/(60*60*57.3radian/") * 100AU * 1.5e8 km/AU ~ 2700km.

If you read the article, you'll find that the size is only 1400km, though.
The difference results from the fact that the measured size of 1.5 pixel
includes the size of its point spread function for the HST/ACS/HRC (i.e.,
even a true point source show some finite size in optics...something we
cannot beat).

Re:Size

[mabinogi]

> It can be derived with trigonometry:

But you still need the scale.

> (1.5pixel*0.025"/pixel)

So where'd you get the 0.025 from?
Without that, 1.5 pixels is completely meaningless. a "pixel" could be any size

Re:Size

[product byproduct]

Hubble's highest resolution should be common geek knowledge, like Mount Everest's height or the distance to the moon. Anyway, here's a quote:

"Images from the HRC are smaller in pixel size, 1,000 pixels square, but have a finer resolution, 0.025 arcseconds per pixel. The HRC is preferred for images of planets, or objects appearing smaller on the sky, where higher resolution outweighs larger field of view."

http://hubblesite.org/newscenter/newsdesk/archive/ releases/2005/34/image/m

Re:Size

[Anonymous Coward]

I am astounded that your calculation uses inches for the size of a pixel bur then gives the result in kilometers. Any self-respecting geek would have done that entirely in SI units.

Re:Size

[heinousjay]

Yes, but any self-respecting person wouldn't be a geek. It's a quandary.

Re:Size

[Anonymous Coward]

Yah and the damned fuzzy logic they use in astronomy has a HUGE fudge factor in there.
1/2 a pixel? that is no way to measure that accurately. it could be carker but 3/4 pixel or only 1/10th a pixel and a star in the same location.

It's redicilous in every way it's either 1 lixel in size or 2 pixels in size (making it a disk instead of a ball)

I hate astronomy simply because of the Gigantic FUDGE factor they get.

Re:Size

[imsabbel]

I am quite sure that in this case " " " (damn, how to you quote a quotation mark?!) should mean arcseconds.

Of course, then it ISNT geometry at all, but using a known formula (as its not THAT easy to unfould the path of light through the telescope onto the ccd including corection lenses)

Re:Size

[barawn]

If you read the article, you'll find that the size is only 1400km

~1400 miles. ~2200-2300 kilometers.

Re:Size

[JackCroww]

How about like this? ["]

Re:Size

[maxwell demon]

damn, how to you quote a quotation mark?!

Everyone here should understand "\"".

Re:Size

[helioquake]

Oh now I feel stupid. It must have been the medicine with Codeine I've been taking.

Re:Size

[wildsurf]

Hubble's highest resolution should be common geek knowledge

So if I attached Hubble's lens to my digital SLR camera, what zoom and f-stop would it be? 10,000mm / f0.1?

1.5 pixels!!

[ithaqua23]

Isn't the definition of a pixel, that it can't be one and a half!

Re:1.5 pixels!!

[Anonymous Coward]

This is true of a monochrome screen, but Hubble has grayscale vision. The object could have registered as 0,0,255,128,0,0 or 0,0,64,255,64,0,0 or something like that.

Obl Futurama quote.

[forgotten_my_nick]

PROFESSOR FARNSWORTH: I'm sorry, Fry, but astronomers renamed Uranus in 2620 to end that stupid joke once and for all.

FRY: Oh. What's it called now?

PROFESSOR FARNSWORTH: Urectum.

Re:Obl Futurama quote.

[Anonymous Coward]

Want to smell it?

Kill Xena...

[Ekhymosis]

...kill Xena

I thought network television did that...

Re:Kill Xena...

[slashdotmsiriv]

" "...kill Xena"

I thought network television did that..."

You are wrong, she came back as a Cylon ...

Anyone care to...

[mrjb]

...post a link to the image?

Re:Anyone care to...

[Zaatxe]

in http://www.milliondollarhomepage.com/ you can see thousands of pixels and until some time ago you could even own some!

Re:Anyone care to...

[tommy_teardrop]

http://www.gps.caltech.edu/~mbrown/planetlila/hubb le.jpeg

Excellent

[Burb]

As every Dr. Who fanboy knows, the tenth planet is named Mondas. http://www.drwhoguide.com/who_2d.htm/. What is slashdot coming to?

Re:Excellent

[dodobh]

As every real; Slashdotter knows, the name is Rupert.

Re:Excellent

[Burb]

I may have known that at some time, but have probably forgotten.

Re:Excellent

[cliffski]

start buying gold, like NOW!

Kill Xenu?

[Negatyfus]

Kill Xenu? You can't say that about my religion! I'm gonna sue you! I'll see you in court!

Re:Kill Xenu?

[mobby_6kl]

... in England!

Re:Kill Xenu?

[Opportunist]

Actually, if we think of the same religion, you should be happy that someone finally deals with that bastard.

Re:Kill Xenu?

[XdevXnull]

Court? If recent events have taught us nothing, let us remember that RIOTING is the proper way to deal with religious differences. Perhaps burn down some restaurants based out of countries other than the one that originally offended you.

Or wait, maybe that's what you do when your football team loses. Or wins.

Xena FTW

[JavaFTW]

Xena: Warrior Princess. LA LA LA LA LA!!! I wish I knew a girl as cool as her!

Re:Xena FTW

[Anonymous Coward]

You just wish you knew a girl.

Re:Xena FTW

[JavaFTW]

Yeah, I stuck my last one in the closet and she got punctured...duck tape didn't help. Sad.

There's a reason why planet isn't defined...

[Vellmont]

It's because the word planet isn't really a scientific word. There's no hard point where something becomes a planet and where it's not a planet. Words like planet are really just our own convienent language definitions. Arguing about whether something is a planet or not is a little like arguing whether something is a chair or not. It only matters based upon useage.

Re:There's a reason why planet isn't defined...

[splodger75]

It's a chair if a certain Microsoft CEO can throw it.

Re:There's a reason why planet isn't defined...

[TapeCutter]

Yes, that is precisely why scientific papers go to great lengths to define key terms. Humans, (and it could be argued, animated lifeforms in general), categorise things to make sense of the universe. Humans go a step further than most animals, they attempt to translate those categories into a common language. eg: To answer the question "is a virus alive", you need to define "virus" and "alive". "Do galaxies evolve", is another question fraught with definition problems.

Simarly, to answer the question "is Pluto a planet", you need to define "planet", defining Pluto is as easy as pointing at it. Most astronomers would answer yes because of convention. Few (none) would go to the trouble of scientifically defining "planet". The name of the game is publish or perish, categorising some heavenly body 'X' as either a planet or a big rock is hardly a "scientific contribution", therefore it adds nothing to the "publish" side of the game.

Category problems are ubiquitous, and my guess is, they expand expotentially faster than the rate of new concepts. In fact a large portion of slashdot threads are fueled entirely by the same problems, just look at the number of posts questioning/defining the meaning of 1.5 pixels. Taking advantage of this kind of confusion to manipulate others is what is known as "spin" (eg: Economic modeling trumps climate modeling).

Of course Louis Carroll said it succinctly and with more elequonce than I can muster...

'When I use a word,' Humpty Dumpty said, in rather a scornful tone, 'it means just what I choose it to mean--neither more nor less.' 'The question is,' said Alice, 'whether you can make words mean so many different things 'The question is,' said Humpty Dumpty, 'which is to be master--that's all.'

Re:There's a reason why planet isn't defined...

[mwvdlee]

Translation of parent:

There's a reason why planet isn't defined... ...is because planet isn't defined.

Re:There's a reason why planet isn't defined...

[Vo0k]

Nope, chairs he throws are just exceptions.

Re:There's a reason why planet isn't defined...

[EZLeeAmused]

I don't know how official it was, but somewhere recently I read a definition for planet. It was among a set of 4 astronomical objects: planet, comet, asteroid and moon/satellite. I think that for a planet, large enough for it's gravity to pull it into a roughly spherical shape, posessing an atmosphere (didn't specify density or composition) were among the criteria.
FWIW, the same article mentioned that whether or not Pluto is a planet is occasionally debated in the media, but that the responsible scientific community doesn't question its planethood any more than they question whether or not the earth is round (ok, an oblate spheroid).

Re:There's a reason why planet isn't defined...

[aqfire]

Arguing about whether something is a planet or not is a little like arguing whether something is a chair or not. It only matters based upon useage.

So I guess the more important question is, how do you use a planet?

Why is this so hard?

[jpatters]

I don't understand why this is so hard to understand. The only sensible definition for a planet is an object that is spherical due to its own gravity, orbits a star, and is not itself a star. But these bozos keep saying "But Pluto is so different from the other planets, we can't call it a planet!" Well boohoo. So it's freaking different! Earth and Jupiter are somewhat freaking different from each other, last time I checked, but we call both of those objects planets! "But then there will probably be a thousand planets in the solar system!" they say. I say, get over it! This is not a big problem unless you're an astrologer! I honestly don't give a rat's ass about Pluto's legacy as being called a planet, if we are going to continue calling it a planet then we also need to call this other object (and several others) planets as well. The problem is, we keep being told that this needs to be controversial because defining a planet is somehow difficult, what I think is happening here is that there are a group of scientists who have an emotional problem with there being a thousand planets in the solar system and are preventing the IAU from adopting the obvious definition.

Re:Why is this so hard?

[jmv]

The only sensible definition for a planet is an object that is spherical due to its own gravity, orbits a star, and is not itself a star

OK, so any mass of liquified gas orgiting the sun would qualify, right? How about comets (if they are spherical)?. Oh and how about we say the moon is orbiting the sun and the Earth is just going around it?

Re:Why is this so hard?

[bdeclerc]

Well, for one, comets are not spherical - and a comet's coma is not spherical due to gravity, which is almost non-existant from an object the size of a comet's nucleus... So we can scrap comets from your list.

The moon : wel just claiming the moon orbits the sun and the earth is going around it is nice for you, but that doesn't make it true... The center of gravity of the Earth-Moon system is *inside* the Earth and the Moon orbits the Earth. - So we can scrap the moon from your list...

Now, Jupiter and Saturn fall under "any mass of liquefied gas" since the majority of their mass consists of "liquefied gas"... Any "mass of liquefied gas" light enough to not be spherical under its own gravity is going to dissipate rather quickly in the solar system, so there are no such objects - no object, no problem.

The main "difficulty" of the definition above is that it would mean that the largest asteroid, Ceres, is actually a planet, since it is quite spherical due to its own gravity.

And since the center of gravity of the Pluto-Charon system falls somewhere in space between the two objects, I would be much more inclined to call Pluto-Charon a "Double Planet" rather than a "Planet+Moon".

I don't see many real problems concerning the definition above, it would work perfectly, the only "problem" it has is that we would have a few more planets, including a new one in the inner Solar System - which to me sounds like a perfect trade-off for a consistent scientific definition. (although there may be a gray zone between what is a "planet" and what is a "brown dwarf", although we could just hold "brown dwarf" to be a class of planets, just like we currently have "terrestrial planets", "gas giants" and "Ice Dwarves"...)

Re:Why is this so hard?

[molo]

By that definition, Ceres, the largest and first discovered asteroid, is a planet. See: http://en.wikipedia.org/wiki/1_Ceres

-molo

Re:Why is this so hard?

[SlayerDave]

Sure, Ceres is a planet. What's wrong with that? Probably several other large asteroids meet the definition too. One could exclude asteroids by requiring the object in question to contain the majority of the mass in its orbit. Since Ceres contains about 40% of the mass in the asteroid belt, it wouldn't meet this definition. Of course, there is the question of how to define the orbit precisely.

Re:Why is this so hard?

[SlayerDave]

As I posted elsewhere, you could deal with the Pluto-Charon issue and the Ceres issue by requiring the object in question to contain the majority of the mass in its orbit. So since Ceres contains about 40% of the mass of the asteroid belt, it wouldn't be a planet. And since Pluto's mass is much greater than Charon's, it would be a planet and Charon would be it's primary satellite.

Of course, I have no problem with Ceres being a planet and Pluto-Charon being a double planet.

Re:Why is this so hard?

[Atmchicago]

You raise interesting points, which lead me to this: what difference does it make if we label an object in space a planet, comet, meteor etc.? Objects in space that are not stars tend to be so different anyway that any label will not be informative. So calling one thing a planet and another an asteroid doesn't get us very far into understanding what they are. We only gain a vague sense of size. Then we have Pluto, which highlights the vagueness of our definitions in the first place.

Additionally, a reason we may have a hard time with adding planets to our solar system is that we were all brought up thinking our planets were special. There are only these planets, and no more! Science has no problems redefining itself over time, but individuals can have those problems. The naming system is a big controversy over nothing, and the more important things to do is study the objects and to understand them better. Calling it a planet doesn't change what it is.

Re:Why is this so hard?

[whitehatlurker]

what difference does it make if we label an object in space a planet, comet, meteor etc.?

Meteors are extra-terrestrial objects which have entered Earth's atmosphere. I think we may want to keep track of those differently.

Re:Why is this so hard?

[Bullet-Dodger]

Only on Slashdot could we be personally offended by astrological naming conventions.

Re:Why is this so hard?

[Gary W. Longsine]

Mainly it's hard because people would like to be able to remember the names of the planets, make posters and whatnot for little kids, write poems about them, name them after greek gods, etc., but it turns out that there are hundreds of round objects circling our sun. Not enough greek gods to go around, and too many for the average person to memorize for sure, especially when they have catalog numbers instead of interesting names.

Re:Why is this so hard?

[aqfire]

The Earth is more of an oblate spheroid so technically by your definition it's not a planet. ;)

What constitutes a "planet"?

[gameforge]

First of all, IANAA (an astronomer).

[rant]
It's truly amazing that we can see things so far away with our little technology; but ultimately, humans have made it so far as the moon... with respect to our sandbox in the universe, that's not very far. Jupiter and Mars are completely different things - they probably were created via entirely different processes. Mars is a dusty rock that gets hot & cold a lot. Jupiter is a massive ball of gas that has thunderstorms with its moons; I read somewhere that one of Jupiter's moons has a tidal terrain. Could you imagine the crust of the Earth rising and falling some-odd hundred meters as the moon went by? One (many?) of Jupiters' moons has this property.

We need a name for balls of mass (whether a few km in diameter or an astronomical unit, e.g. 93 million miles, in diameter) that orbit stars for a living. If that's a planet, fine. Sounds like comets, Pluto, Xena, and everything else that orbits a star is a planet. Otherwise, a "planet" is a name for the eight terrestrial entities that astronomers have known about for centuries... and we still need a name/class system for things that orbit parent stars. Many (most?) argue that comets and the like are not planets because they came to be and exist in a different way than our traditional "planets"... but our own (8 or 9) planets are so very different to begin with, that if you think about it long enough, they're all too radically different to be in the same class. We may like to think we know how Jupiter and Mars and Earth and the Moon were created; that crap happened so long ago, it's safe to say that humans have no way of knowing - none of us were there.

I like the second article, which suggests we demote Pluto and Xena (and similar objects) to "dwarf" planets.

We're only human! For a long time we thought matter and energy were two different things; now, the fact that matter is considered "solid" is coming into question. It goes to show how little we really know to begin with, and arguing the definition of a "planet" is as useful to our curiosities as arguing the difference between a rabbit turd and a cow pie.
[/rant]

So as not to only rant, I thought I would try to be informative as well. :)

If anyone would like to see Xena, here's a page with a decent shot. The actual NASA feature about the recent picture is here.

Re:What constitutes a "planet"?

[dino213b]

I like the google ads that pop up on that first page. "Xena warrior princess season 1"

Re:What constitutes a "planet"?

[The-Bus]

First of all, IANAA...

I read this as "First of all, NIAANA-NYAANAH-NIAAANAAHH!" at which point I thought you were one of the tenth-planet naysayers coming back to show off how right you were in your original prediction.

The Plan

[suv4x4]

NASA secretly discovers disturbing facts about the nature of the tenth planet, and decides the news is too shocking for the wide audience. A plan is created to announce the news in several manageable bites:

1. tenth planet not as big as previously thougth, it's more like a small planet, but hey it's a still a friggin 10-th planet, right!

2. tenth planet not a planet as previously thougth, it's more like a moon of Pluto.. but it's still a friggin planet, if not THE 10-th planet...

3. new moon not really a moon, turns out it's more like a really big meteor, so big, it's kinda as big as a moon, almost, but not exactly...

4. big meteor kinda smaller than big, more like, medium meteor, still there though! xena, the medium meteor!! Yei!

5. ok maybe it's not that of a medium, more like a small meteor, little warrior meteor thingy.

6. hey what did you know! that little meteor thingy noone really friggin cares about, was a smudge on the Hubble lens system! huh, sh*t happens, but it's not like we confused it to be the 10-th planet in the Solar system, I mean, cut us some slack, come on :)

7. hey watch us drink cola in zero gravity. wobble, wobble, wobble, wobble!! lol!

Statistical

[EmbeddedJanitor]

You can measure "sub-resolution" size by taking repeated measurements and averaging (eg. count the number of pixels ten times and average). This is quite commonly done with a wide variety of sensors to get better resolution than the sensors can provide on a single measurement. Sometime noise is added to the measurements to help improve the resolution.

Stupid name

[Kirth]

Well, what kind of a name should that be anyway? Xena is not a roman god or goddess, not even a small one like Luna, Nike or Pluto.

So if this object should be called a planet, here's the proper list of names to choose from:

Acca Larentia, Alemonia, Anna Perenna, Carmenta, Carna, Consus, Dea Dia, Feronia, Flora, Fons, Furrina, Maia, Nike, Ops, Pales, Pomona, Portunus, Robigus, Silvanus, Veiovis, Vertumnus, Volturnus

everything else is not acceptable.

Re:Stupid name

[mgblst]

How about this line from the article
 
  Nicknamed "Xena," 2003 UB313 was discovered last year.
 
So 2003 UB313 was discovered last year, in 2005 - doesn't that strike someone as a little odd.

Re:Stupid name

[renoX]

Why wouldn't it be acceptable?
Why should planets/asteroids only be named after gods?

IMHO Xena is a name that more people know that all the name you gave, so it's easier to remember thus it's a better name.

Re:Stupid name

[miro f]

one billion dollars says "Nike" is picked

Once a higher resolution picture is taken the 1.5 pixels will resolve itself into a tick...

Re:Stupid name

[glwtta]

Xena is not a roman god or goddess

Well, Xenia is one of the many epithets for Athena (so, Minerva, if you want the Roman corruption). From 'xenos', probably referring to her hospitality related "duties".

Incidentally, how did you pick your "proper list" from the hundreds of Roman deities? (Nike is the Greek form btw, Victoria is the Roman equivalent)

Re:Stupid name

[darklordyoda]

I dunno, I'm kinda hoping for the "Fons".

Re:Stupid name

[stunt_penguin]

That said, I'm sure Nike (the sportswear makers) wouldn't mind having the planet named Nike. They can probably use it in an advertising campaign or something. Also, quasi-planet Nike would be around for much longer than sportswear-Nike. Nothing lasts forever.

Re:Stupid name

[Anonymous Coward]

Xena is not the official name, it's just the designation used by its discoverers until the International Astronomical Union decides on a name. Why does it take almost a year to decide on a name? Becouse they haven't decided yet if it's a planet or not. Planets are named after major Roman gods or godesses, while other major KBOs are named after gods associated with the underworld in various mythologies. So until they decide whether 'Xena' is a planet or not they can't name it becouse they don't want to brake the naming scheme.

Re:Stupid name

[TrevorB]

IIRC, the discussions at the astronomical society have come to the conclusion that most of the good roman names have been used up. They're talking about moving into other pantheons for names (Hindu I believe was considered).

It better be a big set of names if we're going to start naming all the large Kuiper belt objects we're going to find.

Re:Stupid name

[Oswald]

Well I'll be damned, you're right. When I read "discovered last year" in the article, I naturally assumed that Slashdot had posted another 2 year old story as "news," but according to the story's date it's current. Good catch.

Re:Stupid name

[Jugalator]

everything else is not acceptable.

Heh, now a Slashdotter made this unintentional imitation of the comic book guy in Simpsons again. ;-)

Re:Stupid name

[Vo0k]

AFAIR Romans had so many deities, covering nearly every aspect of their life, that the above list would be far too short.

Re:Stupid name

[Anonymous Coward]

everything else is not acceptable.

So, which roman god is called Earth again...?

- Peder

Re:Stupid name

[Anonymous Coward]

I'm being little pedantic (or maybe a lot pedantic) but rather than a "corruption" of Athena, the Roman Minerva traces lineage back to the Etruscan Menrva. As the article notes, depictions of Menrva coincide pretty closely with the Greek Athena, but all over the Mediterranean you find the same basic pantheons. Some of the Etruscan origin theories place them in Lydia, or south central Europe so that could always b e a connection.

Besides, Fabulinus is a minor Roman god of infants. Seems mostly approriate for this planetlet...

Re:Stupid name

[MustardMan]

What a stupid idea. As far as I know, there aren't many people out there who still worship the Roman gods. There are plenty of practicing Hindus, though. Using names of figures from an active religion is just ASKING for a public relations nightmare.

Re:Stupid name

[accessdeniednsp]

Sweet! I vote for Fons, he's teh coolest. I'd be somewhat wary, tho, when it jumps the shark, too. That would a rough day for everyone.

Re:Stupid name

[CptNerd]

I dunno, I'm kinda hoping for the "Fons".

(thumbs out) Ayyyyy!

Re:Stupid name

[Anonymous Coward]

We have *LESBIAN PLANETS* and you're complaining? Where did your humanity go? ;)

Re:Stupid name

[Citizen of Earth]

Xena is not a roman god or goddess, not even a small one like Luna, Nike or Pluto.

I think Xena and Buffy are prefectly fine names. The Roman-God names are just drawn from the fictional mythology of the era in which many of the planets were discovered. I think the silliness that we may associate with Xena and Buffy is merely the same silliness and unimaginitiveness that many medical terms would have if we translate them literally into English.

Also, the discoverers wanted to use a name that started with 'X' to point out that they discovered 'Planet X'.

Re:Stupid name

[nytes]

Lucy Lawless is gonna kick your ass.

Re:Stupid name

[jmichaelg]

IIRC, the discussions at the astronomical society have come to the conclusion that most of the good roman names have been used up.

Your recollection has nothing to do why the object is sometimes being called Xena. The discoverer, Brown, named it Xena on a whim. Though he discovered it, it wasn't his perogative to name it. The fact that he issued a press release with a name has caused no end of grief to folks who want a consistent naming scheme.

There are a couple of database maintainers who hand out temporary names like 2004 VD17. If you're conducting research on that particular body, you publish all references to the body as 2004 VD17. That way, if someone wants to followup on what you're talking about, there isn't any ambiguity. Brown flipped the finger to that convention by coming up with Xena.

Re:Stupid name

[whitehatlurker]

Hey, I know of people who worship Xena. That should count, shouldn't it?

You also missed the popular choice of "Vulcan".

Re:Stupid name

[fbg111]

Ah, should have named it Xenu. We could have had a great joke at Scientology's expense...

Re:Stupid name

[aqfire]

And they definitely can't name the 10th planet "Nike" since it's already copyrighted.

Re:Stupid name

[Kadmos]

IIRC the data that was analysed to discover 2003UB313 was from 2003.

Re:Stupid name

[dsanfte]

"IMHO Xena is a name that more people know that all the name you gave"

Uh, Nike?

Re:Stupid name

[syukton]

Just because more people are familiar with the name Xena doesn't mean it's a better name. I'm sure many people are more familiar with the name Justin, but does that mean that the next planet should be named Justin? The people who name hurricanes have a system of A-Z with alternating male and female names which has persisted since the naming of hurricanes began. Why should the planets NOT be named after Roman gods, if that is historically exactly what has been done?

Re:Stupid name

[renoX]

> Why should the planets NOT be named after Roman gods, if that is historically exactly what has been done?

A foolish consistency is the hobgoblin of little minds.

Re:Stupid name

[syukton]

And what, exactly, would make this a foolish consistency?

Re:Stupid name

[renoX]

As the proverb said: consistency for the sake of consistency without any reason is foolish or at least boring.

As I've said Xena is quite a famous name (with positive association), the names which were suggested are totally unknown..

If you really wanted to use a God name, use at least some well known name not unknown minor deities.

no need!

[Quadraginta]

Here's a copy of the image itself:

.

Don't forget it's a reversed (negative) image, so Xena itself is dark and the background of space is white.

I think if you look very closely you can see a few faint stars in the background...

Re:no need!

[KiloByte]

Reversed? It looks fine to me...

Re:no need!

[Niebieski]

I think if you look very closely you can see a few faint stars in the background...

Hey! I looked very closely and saw many many stars, very close to one another and of many colors! (mainly red, green and blue!). But these are less than 1.5 pixels; I'd say rougly ~0.3333333333333333333. I wonder how far they are.

Re:no need!

[Anonymous Coward]

mainly red, green and blue

Hmm, the red and blue are probably dwarfs and gigants so they'd
be pretty close and very far, respectively.

But the green....?

- Peder

Re:no need!

[Anonymous Coward]

But the real question is: Does it run Linux?

Yeah, go ahead and mod me troll.

Re:no need!

[nytes]

The red ones are just moving away from you very quickly.

You need to move your head towards you monitor very fast. That will counteract the red-shift.

Re:no need!

[ArsonSmith]

I tried it now I'm dizzy and the red-shift is sort of dripping down the front of my monitor.

Re:no need!

[thePig]

Do not try to cheat.
This is just 1 pixel across.

Where the remaining .5 ?

Re:no need!

[eyrieowl]

you must not have cleartype(TM) turned on....

RTFA

[Anonymous Coward]

RTFA, it says:

"The round world, officially catalogued as 2003 UB313, is about 1,490 miles wide with an uncertainty of 60 miles"

"Since 2003 UB313 is 10 billion miles away [...], it showed up as just 1.5 pixels in Hubble's view."

INFORMATIVE???

[Anonymous Coward]

The pixels discrete points of measurement. They are atomic in that they are indivisible. This has nothing to do with atoms.

Dumb Question

[Wellington Grey]

How do you get half a pixel? Wouldn't that be like trying to get half a bit?

-Grey

Re:Dumb Question

[Anonymous Coward]

half a bit... you mean "0.5"?

Re:Dumb Question

[Voltageaav]

All the Pixels around it were black except for one that was white, and one next to it that was grey, 1/2 white, 1/2 black. The pixel averages everything in the space it covers. I don't know if they actually use black or white or not, but that's how it works. Does that simplify things?

Re:Dumb Question

[Vo0k]

Would you please advance from the Commodore PET era? Nowadays we live in at least 24bit color world. The pixel was #888888, or rgb(127,127,127) if you prefer.

Re:Dumb Question

[Anonymous Coward]

Ok, but if the object is round in shape, how do you align it so that it covers only 1.5 pixels? Or do we assume it is not round in shape?

Re:Dumb Question

[Anonymous Coward]

#888888 would be rgb(136,136,136). #7f7f7f is what you meant.

Re:Dumb Question

[Qzukk]

You're assuming the pixels themselves are square in shape, which may or may not be so (plasma display pixels tend to be rectangular). Of course, not assuming that the object is round is also perfectly fine, since the Earth (if not most of the other planets) is not perfectly round.

Re:Dumb Question

[maxwell demon]

No, half a bit is obviously a system which has sqrt(2) different states, because two of them together have two different states.

Re:Dumb Question

[Anonymous Coward]

Couldn't it just be that it is two pixels across on some images, one pixel across on others, and they have simply averaged the two?

Re:Dumb Question

[ChrisMaple]

Half a pixel is indeed like half a bit. In information theory non-integer bits are common and useful.

Re:Dumb Question

[legirons]

"All the Pixels around it were black except for one that was white"

Meanwhile, the manufacturers of Hubble respond that they won't repair it until another 3 dead pixels are found...

Re:Dumb Question

[Trogre]

heh, thanks. Best laugh I've had today

Wrong end?

[ozmanjusri]

The Tenth Planet Shrinks Under Hubble's Gaze

I bet they're looking at it through the wrong end of the telescope. If they turn Hubble around, that thing'll turn out to be HUGE!

Re:Wrong end?

[javaDragon]

There is a slight problem : Hubble is a reflector (mirror), not a refractor (lenses), so if you turn it around, you will see Hubble's butt, not Xena's. It might be huge as well, but probably not as exciting.

Re:Wrong end?

[Anonymous Coward]

Certainly Hubble's butt doesn't look nearly as exciting as Xena's.

Re:Wrong end?

[What me a Coward]

Peeping Tom's is what i'd call em Xena's nude in the space shower!

    The pervs.

    Terrible pix's they snapped though can't see nothing. :)

orbit planes?

[Anonymous Coward]

From the second article:

Diminutive Pluto's orbit, like that of 2003 UB313, is way out of whack with the main plane in which the other eight planets roam.

Somebody tell me, how is this important in any way or form? While I agree that calling 2003 UB313 and Pluto planets may be bad idea, I don't see this as a valid argument.

classification in western thought

[kwoff]

I've been reading a book recently (The Geography of Thought) on the differences between how Western and Eastern people think. One of the main theses in the book is that Western thought (since ancient Greek times) is oriented toward objects and their classification, whereas Eastern thought (since ancient Chinese times) focuses more on continuous substances and the relationships between them. Another thesis (or corrolary of the previous one) is that Western thought avoid contradictions, whereas Eastern thought invites them.

So I wonder if this is a case (debating the classification of a "planet") where Western-style thinking misleads us. Although this kind of thinking is great for science, at the same time insisting on logic can be irrational: simply wasting time on an issue that is inherently complex and not either-or.

Re:classification in western thought

[fireboy1919]

I read a treaty by an eastern philosopher who correctly stated that the "both-and" arguement model necessarily contains the "either-or" model, though the opposite is not true. So...it doesn't help.

What that translates to in this case is that not classifying it to accept both conditions (planet and non-planet) is a classification in and of itself - as "unclassified". Either it's classified or its not. See how the either-or emerges?

This is a simplification of the argument, but the gist of it is that the Eastern mechanism is actually a cultural obscuring of naturally occuring logic - which is not Eastern or Western, but is rather the way the world works. The world is filled with objects which are classified, and with substances and relationships which are also chocked full of classifications in order to allow for reasoning.

Re:classification in western thought

[Anonymous Coward]

how does that logic follow? West and East thinking is different. Therefore, western thinking may be misleading. Could just as well say, therefore eastern thinking may be misleading. Your first point is valid, but I don't see the correlation, much less causation.

Re:classification in western thought

[maxwell demon]

What that translates to in this case is that not classifying it to accept both conditions (planet and non-planet) is a classification in and of itself - as "unclassified". Either it's classified or its not. See how the either-or emerges?

But if you classify it as unclassified, then isn't it both classified (namely as unclassified) and unclassified (because that's what it is classified as)?

Re:classification in western thought

[fireboy1919]

Nice try, but it's not a contradiction.

You're using "classified" in a way that requires two different definitions of the word.

Under the first definition, "labeled a planet or not" the thing is unclassified. Under the second, "bearing a form of label" it is classified. You can have both, because they are not the same thing.

The fact that two contradictions relate never forms the basis of an argument. In cases where it seems so, you're always missing some classification.

It's kind of like that old argument:
1) Nothing is better than total happiness.
2) A ham sandwich is better than nothing.
3) Ergo, a ham sandwich is better than total happiness.

The problem is not a contradiction, it's that the two values of "nothing" have different meanings. Which brings us to why we end up classifying things: for the most part, classifications are used to identify logical fallacies caused by similar things being treated as the same thing.

Obligatory joke

[TrevorB]

The following joke just came to mind...

Your momma is so big and so cold they launched her into space and couldn't figure out if she was a planet or not!

OK, that was a crappy joke.

I'd have to agree with the "no 1000 planets, please" antagonists. Defining Kuiper belt objects as planets demotes the concept of "planet". We might as well call every object that orbits the sun "space thing" and be done with it.

In the time it takes to.....

[jameskojiro]

Have Dr. McKay explain this to Conan and Xena the sun will have boiled earth to a smoldering cinder.

What did Mike Brown Really say?

[bloodstar]

From TFA:

The reasons are simple. Even Mike Brown says there is no scientific basis for calling 2003 UB313 a planet. Here is what he said last year:

I will not argue that it is a scientific planet, because there is no good scientific definition which fits our solar system and our culture, and I have decided to let culture win this one.

He's using Mike Brown's acceptance of the generally accepted cultural view that planets are 'anything pluto sized or larger' as a way of discrediting 2003 UB313. In fact, Mike Brown had felt previously that the definition of Planet was unsatisfactory and threw out some ideas on how the definition could be altered. http://www.gps.caltech.edu/~mbrown/sedna/index.htm l#planets links to the text in question. Mike Brown has since come to the conclusion that culture is going to decide what defines a planet, not a bunch of scientists. So basicly, unless the scientists who want to change the definition of a planet can convince society to listen, it's going to be like a tree falling in a forest with no one around to hear it. Sure, it happened, but who cares?

Re:What did Mike Brown Really say?

[I am Jack's username]

Strange that a scientist would not see the problems with such a fallacious argument, especially since 79% "of Americans believe that, as the Bible says, Jesus Christ was born of the Virgin Mary, without a human father" and 62% "say they favor teaching creation science in addition to evolution in public schools". Shall we give up the word "theory" next?

As for Pluto, please see 4 Vesta's history.

a name is a soundbite

[Anonymous Coward]

I'm an astronomer (in a different sub-field), and I'm pretty happy with the situation as it stands. The whole is-it-a-planet-or-not debate gets people interested in astronomy, but it's of essentially no significance to us. It's only a name, we care about the reality of things and not the invented names given to them.
This is a cynical way to put it, and maybe some other astronomers care more than I do. I'd certainly like it if people were more interested in cutting edge research (or detailed politics, computer technology...) than naming stuff: a name is the ultimate in empty media-friendly soundbites. Still, everyone is comfortable expressing an opinion in this debate, it's nice like that.

Re:a name is a soundbite

[Anonymous Coward]

I do believe that's the most insightful comment I've seen in this debate yet. Kudos.

In other news...

[Jugalator]

New images of 2003 UB313 (aka Xena) were delivered by the Hubble Telescope and showed up as only 1.5 pixels!"

... it was soon after discovered that according to current theories, moving closer to the 10th planet would make it show up as 3 pixels, and even 6! Scientists worldwide are baffled at this discovery, and one was quoted as "if we send out a space probe far enough, it could even cover an entire screen of several Megapixels". This claim was however met with scepticism, with many still claiming that this planet is indeed just 1.5 pixels large, as the trustworthy Hubble Telescope indicates.

Re:RTFA (OT from article)

[Anonymous Coward]

Quit your whining.

The GP was only complaining about the summary and as a summary, it should concisely explain relevant information from the article. It failed to do that as it never mentioned the scale. The summary should have either mentioned the scale or not said anything at all about how many pixels the 'planet' takes up. RTFA should NOT have to be done to make sense of any part of the summary. If I wrote an executive summary that forced my boss to read the original report to make sense of it then I would be fired. I thought this shit was quite obvious....

Demote Pluto?

[nurb432]

Sounds like its time for a lynching.

It's not tiny...

[Anonymous Coward]

It's just "small boned".

Schrodinger's Cat

[yeolcoatl]

Mother Very Easily Made a Jam Sandwich Using No Peanuts, Mayonnaise, or Glue

What does half a pixel look like?

[bareman]

How does one display "half a pixel"?

I'm guessing greyscale, but still the idea of half a pixel strikes me as somewhat funny.

ps. Kudos to the person who posted the "." as a substitute for a link to the image. You made my day.

Re:What does half a pixel look like?

[What me a Coward]

How does one display "half a pixel"?

    With great care and prescission.

    A healthy imagination helps to!

    It's a dog... No a penguin... No a fro.... Sorry i was right the first time it's a dog definatly a dog.

The Science Types will Hate this but...

[Hercules Peanut]

Couldn't we just say that since Pluto was granted planetary status that its size defines the criteria for becoming a planet? Anything smaller than Pluto is not a planet and anything larger is a planet?

It really seems very subjective to me and this way, we could all move on with our lives.

Re:The Science Types will Hate this but...

[maxwell demon]

What about the Moon (which is larger than Pluto)? Shall we relabel the Earth/Moon system as double planet?
Of course that would be nice for NASA, because in that case they already sent humans to another planet! :-)

Re:The Science Types will Hate this but...

[geekoid]

There is no definition of a planet. Hence the problem.

Personaly, I would say the Nine are planets(for tradition) in the future a body with an atmosphere is a planet.

Re:The Science Types will Hate this but...

[What me a Coward]

The planet moon?

    Now that would be a double standard. :D

No...

[Otto]

It's Persephone. It's nicknamed Rupert, after some astronomer's parrot.

Heliocentric Definitions

[SeanDuggan]

For that matter, even if we add in language saying that it has to orbit a star, what does that do to the binary-star systems were the stars are rotating each other?

Ummm...Actually, Nibiru is it's name

[Sabathius]

Nibiru, to the Babylonians, was the celestial body associated with the god Marduk. The name is Akkadian and means 'ferry boat', 'crossing place' or 'place of transition'. In most Babylonian texts it is identified with the planet Jupiter; in Tablet 5 of the Enûma Elish it may be the pole star1, which at the time was Thuban or possibly Kochab. According to writers Zecharia Sitchin and Burak Eldem (q.v.), Nibiru in Sumerian records referred to an undiscovered planet, but these claims are not taken seriously by experts in archaeology or astronomy.

define "spherical"

[Anonymous Coward]

Then there's the problem of defining "spherical", and the planet wars erupt all over again. Earth is sort of spherical, but squashed a bit, so we get into how squishy/bumpy/whatever still qualifies as spherical enough.

Re:atomic? - cleartype?

[elmarkitse]

If as a later poster suggests, you're referring to 'atomic' as the smallest possible unit, or something indivisible, then you should do some reading up on cleartype. My understanding is that each visible pixel on your screen is made up of a few (RGB?) sub pixels which turn on in different intensities to create the 'pixel' you see. Microsoft and some others apparently discovered that if you 'steal' some of the sub pixels from adjacent 'pixels' and activate them, you can soften hard edges, effectively an antialiasing effect visually. I'm not an expert, I didn't read the article, and I know very little about how the hubble imagery is created, but I'm putting my money on that half pixel being something like what I described above.

cheers

Give it to the Investigators at CSI

[aplusjimages]

According to the TV show CSI, they can take that pixel increase the image size and then enhance it enough to make out all the different geographical terrian on the planet/object in space. I tried it in Photoshop and it just doesn't work.

Re:Give it to the Investigators at CSI

[Golden Section]

I tried it in Photoshop and it just doesn't work.

'Cause you didn't install the CSI Image Zoom plug-in from Bruckheimer Software.

Re:Give it to the Investigators at CSI

[aplusjimages]

Do you know where I can get a pirated copy? I mean a trial copy. I want to help NASA with this planet problem.

my wacky scheme, for what it's worth:

[circletimessquare]

i disregard what something orbits in my home cooked scheme:

• anything earthlike (small, mostly solid, sphere, appreciable atmosphere): planet
  
  that means mercury is not a planet. but titan is
  
  
• anything like the moon (small, mostly solid, sphere, no atmosphere): moon
  
  that means mercury is a moon. so is pluto. so is ceres
  
  
• anything like jupiter (huge, mostly gas): gas giant, enough said
  
  
• anything like phobos/ deimos (small, nonspherical, all solid): asteroid
  
  
• then you have the comets (small fragile compacts of dust and ice)
  
  
• and rings
  

that's it

so the key is you classify something on its composition, regardless of what it orbits

therefore you would talk of moons of the sun (mercury, pluto) versus moons of uranus, planets of saturn (titan) versus planets of the sun, and asteroids of mars (phobos/ deimos) versus asteroids of the sun

you even have asteroids of asteroids (ida and dactyl) and moons of moons (pluto and charon)

we even have a binary moon of the sun (antiope the "asteroid")

i firmly believe this nomenclature wuild be more useful as we will come to see lots of more planetary systems out there, some quite exotic, with secondary planetary systems orbitting gas giants (which you can say saturn and jupiter already have) and maybe even TERTIARY systems (moon of a moon of a moon?)

i expect to find suns with rings too (not just planetary rings)

binary/ trinary star systems will complicate things. i expect we will find binary planets sharing an atmosphere, i expect to find planets orbitting nonspherical large asteroids. all sorts of lunacy (no pun intended)

we need a new nomenclature

Re:my wacky scheme, for what it's worth:

[Anonymous Coward]

>i expect to find suns with rings too (not just planetary rings)

Yeah; Sol: It has an asteroid belt. That's a ring, isn't it?

maybe....

[solstice680]

Tenth Planet Shrinks under Hubble's Gaze

Maybe it's because Hubble giggled...

Obligatory Movie Reference

[galonso]

That's no moon, that's a space station.

What the Hell is the Name of this Thing Anyway?

[Phoenix666]

Isn't this the deal they were calling Quaoar or some other goofy name? Changing it to 'Xena' now is hardly keeping us abreast of the situation.

Re:What the Hell is the Name of this Thing Anyway?

[Thrymm]

Quaoar is different...

http://en.wikipedia.org/wiki/(50000)_Quaoar

Says it is a more circular orbit much like all the planets except Pluto which is eliptical and off the plane as well as about 1200km diameter.

Re:What the Hell is the Name of this Thing Anyway?

[sidyan]

50000 Quaoar, 28978 Ixion, 20000 Varuna, 90482 Orcus, 90377 Sedna & others are similar objects already classified as "minor planets". 2003 UB 313 (a.k.a. Xena), 2003 EL 61 (a.k.a. Santa) & 2005 FY9 (a.k.a. The Easterbunny) are still pending review and final classification.

Re:What the Hell is the Name of this Thing Anyway?

[What me a Coward]

I'd like to keep a Abreast of Xena's situation!
    I'd probably get slapped though. :D

Re:Wasn't....

[sidyan]

That would be LV-426 (Acheron).

Xena

[Anonymous Coward]

I'd like to send my probe into Xena to see if she's wet.

Or to reference another TV show

[flyingsquid]

There was shrinkage! Significant shrinkage!

Re:Or to reference another TV show

[Catbeller]

Well, to be fair, it really is cold out past Pluto.

I wish this 10th planet crap would die

[Tycho_Atreides]

Its not a damn 10th planet, its just a large kuiper balt object. So's pluto for that matter. Theyre not really planets, its just that UB313 isnt cool sounding enough to be on a headline. I highly doubt the story "Kuiper Belt object UB313 found to be of different size than previously ascertained".

Re:I wish this 10th planet crap would die

[geekoid]

Pluto had atmospher, and orbits the sun. WHy can't it be a planet?

A poodle is still a dog.

Re:I wish this 10th planet crap would die

[What me a Coward]

On behalf of all Plutino's everywere I take offense man.

We Plutino's are very proud peoples eh planets man and we don like you trying to downgrade us man. My heffe Cubewano feels the same way, We not so happy you trying to stick KBO labels on us either man that's racisum and we get angry.

We Plutino's and Cubewano's will rise up in angry protests and start riots man. If you try and oppress us we cut you, You no oppress the Plutino Cubewano comunity man!

LOL sorry after reading the article and some links and finding thoughs clssifications that whole ethnic thing came to mind. What if the KBO's could argue for themselves. The ethnicity kinda came from the names they got labeled with.

I personally don't think their going to have as easy a time with it if they try to downgrade pluto in the public mindset it's a planet and even if the scientific community starts saying it's not most will still call it that so it would more than likely come out as a non change change that gets changed again to allow for pluto as an exception to the planet rule (whatever planet rule they decide on) to satisfy the majority. Or as one offered they may make a steller line and say everything beyond pluto is a extra solar body and pluto's the last planet making 9.

But if they try to force it on an unwilling public as i said it wont be taken seriously and become a non change despite efforts to the contrary. So they would do better to find a more creative means to solve the issue that still allows pluto to remain a planet and keep other bodies beyond that from being argued should be planets because pluto is one.

Their the bright eggheads they should be able to come up with a solution like that for this that doesn't involve reclasification everytime they find something else new out like KBO's or EKB's/EKO's and TNO's all of which mean the same thing but with different names because they first named the Kuiper belt after the best known man that predicted it Gerard Kuiper in the 1950's so KBO (Kuiper belt Object).
Only to discover that another man somtime earlier had predicted the same thing Kenneth Edgeworth in 1940's so they combined the two names and came up with EKB (Edgeworth Kuiper Belt).
And just to make matters worse they later discovered that some other researchers had predicted the same thing before Edgeworth and Kuiper in the 1930's so the argument went what about them? Do we take out Kuiper and Edgeworth or further complicate the name to satisfy everybody? I guess To settle the dispute and prevent further complications the went politically correct on it and came up with TNO or 'Trans-Neptunian Objects'.
Making matters worse the name of choice among though who insisted on the EKB classification prefered the term EKOs, for Edgeworth-Kuiper Objects.

KBO, EKB, EKO, TNO How many terms does it have to go through and how many times will the planet terms and other terms change with the scientific comunity insisting everybody switch to that everytime they find something new out like with pluto?

It would make people so dizzy and confused they wouldn't know what this or that is called now or what they will be called tommorow. Adding to the name confusion is Plutinos and Cubewanos.
a Plutino has a weighty affinity for Neptune and is in a 2:3 mean motion resonance with Neptune which means it circles the sun exactly twice for every 3 times Neptune does.
Objects near Plutinos that are not attracted into resonances with Neptune are called cubewanos and make up what's called the traditional Kuiper Belt Objects.

Then their are the NEO's and NEA's and PHA's and it's getting to be so many terms and references that it can make your head spin. And were not even done yet but i'll spare everyone haveing to go through anymore just sufice to say their's a lot of diffrent names and terms

1.5 pixels?

[springbox]

You either have a pixel or you don't; unless someone has made a screen that displays fractions of pixels. If they're saying 1.5 pixels, does this mean they're basing their measurement on the value of each pixel?

Re:1.5 pixels?

[adrenaline_junky]

Assuming that each pixel is either ON or OFF, then you are correct.

However, I think what they probably mean (though perhaps were unclear about) is that the image has one pixel that is very bright, and the pixels immediately next to that pixel are maybe "half" as bright. A pixel that is only half-bright would indicate that the object only "fills" half of the pixel.

Thus, the object is 1.5 pixels in size.

Re:1.5 pixels?

[Lord Crc]

You either have a pixel or you don't

For a regular image, that is mostly true. However in the case of stars and such, you have a bright object over a usually uniform dark background. This allows you to compute how much energy each pixel has, and this again allows you to calculate the fraction of star/planet in each pixel, so to speak.

Also, you can capture an image sequence. Between images the vantage point changes slightly. By combining these images and correcting for the change of position, you can get an image which has a much higher resolution than the sensor. Lately, amateur astronomers have been using this technique, allowing them to make very good images using cheap webcams.

Re:1.5 pixels?

[Anonymous Coward]

unless someone has made a screen that displays fractions of pixels

They have, and they're called TFT monitors. Usually one pixel is made up by three transistors which light up in individual colors - red, green, blue.

Anyway, this astronomy junk is just boring. Who gives a shit about planets? We got problems on this one, let's deal with them first.

Objects should be classified by common features

[Xerxes314]

The problem with this definition is that sphericity is not an interesting property.

The classes of object in the Solar System (according to shared features) are:

1. Gas Giants
2. Rocky Planets
3. Asteroids
4. Comets
5. Kuiper Belt Objects
6. Oort Cloud Objects (only Sedna yet observed?)

And then there are some asteroid-like bodies that have wandered off (Apollos, Jupiter Trojans, etc) and some kuiper-like bodies (Centaurs) that have wandered off. Moons are a bit trickier to classify, but we'll ignore them since they're not Sun-orbiting.

Planet is most sensibly defined to be the combination of the first two classes. They share such features as: circular in-plane orbits, large mass, common formation. The most important feature of these two classes is that they are small; four bodies each. A definition of planet that included thousands of objects would not be useful.

Since Pluto and 2003-UB_313 fall into the KBO class (sharing such features as: eccentric orbits, resonance with Neptune, icy composition, medium mass), they are not planets. Pluto was originally mistaken for a Gas Giant-type body; it's not, so it should have been declassified as a planet. However, the KBO class was unknown at the time, and Americans liked the idea of an American-discovered planet, so it got inappropriately included. As for 2003-UB_313, it's hardly surprising that the discoverer thinks that it's a planet, but his opinion should clearly not be taken seriously.

Xerxes

Re:Objects should be classified by common features

[Anonymous Coward]

The classes of object in the Solar System (according to shared features) are:
(...)
      2. Rocky Planets
(...)
Planet is most sensibly defined to be the combination of the first two classes.

Yeah ... A Planet is defined to be a planet ... that makes a lot of sense :-D
Does the term circular definition ring a bell?

Not to nitpick too much, but...

[whitenaga]

#888888 = rgb( 136, 136, 136 )

#7F7F7F = rgb( 127, 127, 127 )

SI Would Cry

[Anonymous Coward]

Oh. We're using the new pixel unit to measure planets now. I'm having troubles learning my new conversion tables, could someone tell me how many pixels wide the Earth is?

Seriously though. Who cares how many pixels wide it is on the Hubble telescope. What matters is how many meters it is. It's hard to tell that just from a simple very far off optical image, and I think we probably shouldn't make snap judgements quite so soon.

Xena Still Bigger

[xocp]

The headline made me think that Xena was now thought smaller than Pluto, but from the article:

The round world, officially catalogued as 2003 UB313, is about 1,490 miles wide with an uncertainty of 60 miles, according to new observations by the Hubble Space Telescope. Pluto is roughly 1,430 miles (2,300 kilometers) wide.

What makes it obligatory?

[Anonymous Coward]

The article is about the 10th planet. Why is a joke about the 8th planet obligatory?

Planet Shrinkage

[Anonymous Coward]

Obligatory Seinfeld quote: it was in the pool!

Again with the obligatory

[Anonymous Coward]

1) Define obligatory
2) Using 1), explain how your joke is obligatory.

I'll agree with crappy, but not obligatory.

Your use of the word obligatory begs the question, "Do you know what you're talking about?"

(Yes, I know, that's why it's in italics, dopes.)

Shrunken

[j2fraser]

It WAS a full-sized planet until it was hit by Dr. Evil's sinister Solar System Periphery Planet-Shrinking Laser Beam (SoSyPerPlaShLaB).

Why demote Pluto?

[mark-t]

I mean, is it really so awful to have an exception to a rule?

Re:Why demote Pluto?

[geekoid]

What rule?

Re:Why demote Pluto?

[mark-t]

Whatever rule they decide to put in place that would have, by strict interpretation, caused it to be demoted.

By your list Pluto IS a planet

[geekoid]

It has an atmosphere. UIt may even exchange it with Charon.(a few molecules at a time)

Erm, no.

[Just Some Guy]

Alemonia

...the Roman goddess of bleeding men dry. I'm not divorced, but I think my less fortunate brethren might want to skip over this one.

are you serious

[Anonymous Coward]

Planet Nike?? I can't believe I just heard someone advocate for a Planet Nike...

How about ...

[willtsmith]

How about a body orbiting a star directly (not orbiting another planet) that within a certain percentage of round and orbiting within xxx degrees along the solar elliptic.

Re:How about ...

[scotch]

Why does the planet need to be in the ecliptic, for that matter?

Re:How about ...

[qazsedcft]

The problem with the "orbiting a star directly" criterion is that one could argue that any planet with moons is not orbiting the star directly, because the planet wobbles from the gravitational pull of the moon. If the moon were large enough the system could be called a binary planet system. That's why the definition of planet must also take into account twin planets orbiting each other.

The ecliptic criterion is an arbitrary human-centric idea, IMHO.

1.5 pixels, OMG!!!!

[pyrrho]

it's bigger than some stars!

still 3x size of Pluto.

Does it "wander" in the sky? Yes? Planet.

"Planet" is an arbitrary term

[Pfhreak]

Any way you define "planet" outside of something simple like a mass or radius limit will have a hazy limit. "Roundness," as in relaxed into an oblate spheroid by its own gravity, has a number of borderline cases already known, not to mention a number of objects that we just don't know about yet, and icy bodies seem to form spheroids at lower masses than rocky bodies, because they're less rigid. Composition doesn't help because the composition of most of the known TNOs is approximate at best, and outright guesswork in many cases. Using some kind of orbital parameters limits the usefulness of the term to our own Solar System, since many of the extrasolar planets that have been found show that there's more than one way for a system to form. Yet, if you use something simple like "objects with a radius of at least X km" or "objets with a mass of at least Y kg" you're drawing a completely arbitrary line.

Basically, I don't think "planet" can ever be a scientific term, because, as many of the large TNOs illustrate, sub-stellar objects form a continuum with multiple axes. Defining stellar objects is relatively easy: they have enough mass to sustain fusion in their cores, or they're the "dead" remnants of such an object. Likewise, Brown Dwarfs can be easily defined as massive enough to trigger deuterium burning, assuming the object has any deuterium left. Gas Giants are also fairly easy to class: no chance of fusion (deuterium or otherwise), and no solid surface. It's not cut and dry for the smaller objects, and I thinks there's always going to be some grey area and borderline cases, no matter what the definition.

I feel sorry for Pluto

[Anonymous Coward]

... and so does this cartoonist.
http://www.thepaincomics.com/weekly050119a.htm

I can't help it.

[Anonymous Coward]

Bueller, Uranus is mine.

yup

[circletimessquare]

but that atmosphere is pretty weak

so there's a chink in my nomenclature: what do you call an atmosphere? i'm sure no matter what density boundary you set, some planet/ moon somewhere will straddle it

ah well

nah

[circletimessquare]

too weak to be considered a ring

which of course raises another point: what's the density at which something is considered a ring? no matter what lower boundary you assert, you'd probably find something somewhere straddling the boundary

so there's always room for controversy ;-P