The Sun's 10th Planet... Sedna?

dsanfte writes "While NASA remains intentionally vague, promising only a news conference Monday, The Australian has the details. The new planet, dubbed Sedna after the Inuit goddess of the sea, is 3 billion km further from the sun than Pluto, and is slightly smaller at 2000km in diameter. This discovery has apparently reignited the debate as to how big a solar object must be in order to qualify as a 'planet', but it is significant nonetheless."

Comments

Re:How could

[dreamchaser]

Because you have to be looking at the right place at the right time. Do you have any idea how vast a volume of space we're talking about?

It's a Kuiper object...

[meringuoid]

... and the last I heard was that it was about the size of Charon. I doubt it will ever be recognised as a planet - we already have Quaoar out there and swarms of other little Plutinos.

Whether Pluto is 'really' a planet or just a big Kuiper object seems to be a silly argument. Even if it's not justifiable, we'll call Pluto a planet out of tradition.

Re:How could

[phch]

It's always been hard to see distant planets because they don't emit light. Hubble can see distant galaxies because they contain lots of luminous objects.

Political Correctness

[schnarff]

I think I can answer all of the people on here who are asking "Why didn't they go with a Roman name?". It's real simple: political correctness. After all, Roman names were given to the planets by a bunch of old, dead white men, and are a vestige of a conquering, warfaring civilization. This new Inuit name represents one of those poor, marginalized, powerless indigenous tribe types. It's like affirmative action for planets.

Personally I think we should have just stuck with the Roman names and kept a consistent system...but then again, I am a middle-class white male. ;-P

Umm...Mars?

[0x0d0a]

don't know if anyone else feels this way, but I'm kind of let down by the fact that our most interesting space story for awhile now is that we MAY have a 10th planet in our solar system.

Umm...what? The past few months have been *spectacularly* exciting from a space point of view. We have two probes that successfully landed on Mars and have found strong evidence that Mars had liquid brine at one point. We have a ton of pictures from the surface to look at, and are expecting tons of findings, papers, and theories based on probe data that's been returned.

And while, yes, the classification may not be interesting, the fact that we discovered a new, sizeable chunk of matter in our solar system is not small stuff either.

Astrology = Syncretic Religion

[handy_vandal]

Still, at least this discovery has the redeeming quality of completely fucking up astrology.

Astrology doesn't work that way.

Astrology is syncretic religion -- it readily (and inevitably) incorporates new influences.

Like an amoeba, astrology engulfs everything it touches.

In this sense, astrology is rather like paranoia: everything pertains, everything is part of the Big Picture.

Sedna won't fuck up astrology. On the contrary, astrologers will eagerly seize on the idea of this new planet, treating Sedna as one more vacuole in the amoeba.

-kgj

on being a planet or something less...

[joebeone]

My former advisor here at UC Berkeley, Gibor Basri, has a neat way of discriminating between planets and the lesser (comets, asteroids, etc.). His idea is that if the object has enough self-gravity to force it into a spherical shape, it's a planet... if it doesn't (like Mars' "moons"), it's something less.

Here's a snipet:

How can this be resolved? A consensus is slowly developing (I believe) for the following solution. We can first define what we mean by "planetary mass", and base this only on physical characteristics. Then we can include circumstance into the definition of "planet". I propose the following three definitions:

FUSOR - an object that achieves core fusion during its lifetime.

PLANEMO - a round non-fusor.

PLANET - a planemo orbiting a fusor.

[...]

read on for his full article.

The following is a draft of an article now published in the Nov/Dec 2003 issue of Mercury. Draft of Mar. 20, 2003.

Defining "Planet" by Gibor Basri Univ. of California, Berkeley

Even before they were civilized, people looked into the sky and recognized different celestial objects. The Sun defined daytime, and the stars provided a fixed background of faint, twinkling lights at night. Among them moved the Moon, and a few special steadier lights. The Greeks called those which moved "planets" (it is worth noting that the Sun and Moon were originally included, since motion against the stars was the defining characteristic). Most cultures have an analogous word for these "wanderers". Both the stars and the planets were thought to revolve around the Earth.

After the Copernican Revolution, we recognize the Moon as the only body that orbits the Earth. The Sun is a very nearby example of a star, and the visible planets are other large bodies that orbit the Sun. We see them by reflected sunlight, while stars produce their own visible light. This understanding yields the dictionary (lay public) definition of the word "planet": a large heavenly body that shines by reflected light and orbits the Sun. In the past century we gained much understanding of our Solar System, and even visited most of the planets robotically. Yet today, professional astronomers find themselves unable to agree upon a succinct definition of "planet". Replacing "the Sun" with "a star" is obviously necessary now that many extrasolar planets have been discovered, but the problem goes well beyond that.

Two recent controversies that found their way to the popular press illustrate further difficulties. One is the "Pluto controversy". This arose because of the discovery of a large belt of icy objects beyond Neptune. They are the outer remains of the original protoplanetary disk. This "Kuiper Belt" is a natural outcome of incomplete planet formation in the outer Solar System, and is the source of some of the comets we see. As Kuiper Belt objects (KBOs) were discovered in increasing numbers in the 1990s, including a population of "Plutinos" which share Pluto's orbital characteristics (somewhat different from the other planets), some astronomers began to suggest that Pluto itself (which shares many properties with, but is the largest KBO known so far) does not qualify as a planet. The recent discoveries of Varuna and Quaoar (which are KBOs half the size of Pluto, like its moon Charon) may presage the time when we find another Pluto-sized KBO.

The current situation is much like that in the early 1800s, when the first asteroids were discovered. Ceres was originally hailed as the fifth planet, particularly since one in its position was expected from "Bode's Law" of planetary spacings. It lost its status within a few years, when other members of the asteroid belt began turning up. Herschel, who had been the only person to have discovered a new planet before then, aided the effort to demote Ceres. The arguments against its planeta

Re:A lot of astronomers don't want to count Pluto

[c1ay]

So where's the line between asteroid and planet? IMO, Pluto should be labeled an asteroid since it's smaller than even our own moon. Of course, there are also asteroids with moons but yet, they are considered asteroids, not planets. And what makes a comet a comet and not an asteroid, it's orbit? It would certailny seem that agencies like NASA that are so concerned with being precise in other areas could could come up with a more precise classification system.

Re:A lot of astronomers don't want to count Pluto

[Jesus 2.0]

Pluto should be labeled an asteroid since it's smaller than even our own moon.

Frankly, I don't understand this line of reasoning. Why does it matter, with regards to whether something is a "planet" or not, whether that thing is bigger than, for example, our moon?

And "asteroid"? Pluto is far, far larger than anything currently considered an "asteroid".

Jupiter and Saturn both have moons that are bigger than Mercury. Do you not consider Mercury to be a "planet", either?

What if Jupiter had a moon bigger than Earth? That's not unimaginable; would Earth then not be a "planet"? In fact, would then nothing be a "planet" except Jupiter, Saturn, Uranus and Neptune?

I frankly don't see what's wrong with (something like) a "planet" being a non-star that's orbiting (directly) around a star. Sure, that makes for some seriously small "planets" relative to what we're used to, but at least it's not an arbitrary and useless definition like (no offense) yours.

And anyway, if you want to add back in your preferred amount of arbitraryness, you can always start referring to "major planets", "minor planets", and so forth.

Re:A lot of astronomers don't want to count Pluto

[catbutt]

So where's the line between asteroid and planet?

Why does there have to be one? Man's tendency is to compartmentalize things, to make sure everything has a name and that name is unambiguous. Problem is, nature doesn't cooperate. There are always going to be intermediate forms, so there are never going to be definitions that aren't arbitrary.

Same thing applies to species. The nice simple definition "if it can interbreed, its the same species" doesn't always work, and there is no reasonable definition that covers all cases and removes ambiguity.

Re:A lot of astronomers don't want to count Pluto

[mysticgoat]

Quoth grandparent: Pluto should be labeled an asteroid since it's smaller than even our own moon.

Quoth parent: Frankly, I don't understand this line of reasoning. Why does it matter, with regards to whether something is a "planet" or not, whether that thing is bigger than, for example, our moon?

I agree with parent that in this case size really doesn't matter: it's all in how you use what you got.

Historically, Neptune was discovered because it was perturbing Uranus' orbit: its existence was theorized long before it was directly observed. Similarly, Pluto was discovered because it was found that Neptune alone was not sufficient to account for all of Uranus' irregularity. While Pluto isn't very big, its size and orbit are such that it definitely affects the other planets.

In practice then, what we have actually used to distinguish a planet like Pluto from a large body that is not a planet, like Chiron (roughly as big, discovered 1977), is whether the object interacts in a measurable way with known planets. If it does, then accord it planet status because it is clearly part of the planetary system.

In view of this, the new discovery is probably not a planet, unless it has a weird orbit like Pluto and would account for some of the remaining difference between planetary observations and expectations.

But what do I know? IANAA.

Re:Woop de fucking do!

[osgeek]

Now, of course that seems like hogwash, and maybe it is, but it is pretty accurate

Bullshit. If it's accurate, then you could come up with a test to prove it. You could take astrological predictions for an individual based upon his house and compare them with random predictions. These could then be compared for statistical validity, proving once and for all that astrology is accurate.

Wow, if only someone would take the time to perform tests like these. Maybe someone could even make a contest to offer money to anyone who could prove a fantastic claim like "astrology is accurate".

Get it through your skull. It's PROVEN TO BE bullshit. It's always been bullshit, and it will always be bullshit. I've had close dealings with astrologists. I know how some of what they say can seem to be more than just coincidence, but that's all it is -- coincidence and psychology. It's got nothing to do with anyone's "house" or "fate". It's all just bullshit. Don't be a sucker.