"It doesn't matter how beautiful your theory is, it doesn't matter how smart you are -- if it doesn't agree with experiment, it's wrong." -- R.P. Feynman
I feel that this quote is appropriate, as I believe this type of simulation possibly cannot contain every essential physics that governs the evolution of the Universe. Some oversimplification must be present and some tweaks (e.g. dark matter) may go into the modeling to match whatever we see it today.
This isn't the end of the study of cosmology. That's all I'm trying to say.
No,no, you've got the signal wrong. My response was to a part of the parent's submission: "put the wood onto..." Not really thinking about comparison between DI mission vs. Lunar Prospector.
That'd be like comparing an apple and an orange.
[The HST and Chandra are scheduled to monitor this event. Wait & see what will take place then.]
No luck finding the preprint so far. But here is the thing.
This is a G0 star, so it's likely to have a similar scale size as our Sun. Looking up Simbad, I see that this star is located roughly 80 parsec away, which isn't too far. Now, this new planet. It is 0.72 times the size of Jupiter. So if you take the ratio of apparent discs, it'd be
or 0.5%. So all you need is to achieve +/- 0.1% accuracy in photometry to derive the apparent size...there, easier said than done. No wonder they needed a big telescope to do this accurately.
I think it's doable, though your points are well taken, too. I wouldn't be surprised if there is a factor of two errors.
That's a very good question. I'm glad you are moderated up for that.
I don't think anyone knows for sure what the planet's environment is exactly like. All they can really tell you are that (1) the planet is quite massive and (2) its phyiscal size. The density at the core is implied from it. And whether it has a magnetic field or a moon, that's still up for debate.
I take it that the interpretation of the dataset is not completely unique. There may exist other types of interpretation. And these guys are just throwing in one of theirs to see how the community would react (I'm not one of them, though I submitted the article).
You're not alone in thinking like that. As a matter of fact, you can look back in history and find that, circa 1900, quite a few people shared the same view about the studies of electrons and X-rays as you do today about planets. They thought, "geez, why the hell are we spending on money to study these useless things like electrons and X-rays? What GOOD WOULD THAT EVER DO?"
Now admittedly this may not be exactly the same kind of discovery as electrons. But the idea is the same; we are trying to understand the environment we live in. With hope that will lead us to better and prosperous life in a long run.
A healthy skepticism is always a Good Thing, I think.
I haven't read the actual journal article, but I'm sure that the paper is accepted by ApJ because error analysis is performed properly. Or so I hope.
Anyway, what distinguishes this work from others (to me) is that many quantitative values (orbital period, the mass and radius of the planet, etc) are measured via observations. That doesn't happen very often in astronomy these days.
Key word: little bit. Given that this happening REALLY far away, and we're only observing it through telescopes, it's almost impossible to measure accurately.
We can measure the effect of wobble quite accurately. The current accuracy is about +/- 1 or 2 meters per second. That's usually good enough to detect a planet like this.
But your points are well taken. There are uncertainties to be considered in the analysis. I'm sure these guys did take that into account in their work.
Let me add to that. We know that a G0 star has roughly the same mass as that of our Sun (*). Once you have some handle on its mass, you can do the following:
(1) examine the wobble pattern of the main star, (2) then examine the effect of occultation (eclipse) by the planet (i.e., when the planet goes in front of the star, the brightness of the star decreases...which gives you a sense on how big this planet is with respect to the star's apparent disc), (3) then use Kepler's third law to derive the size of its orbit,
Now you have two unique information: the orbital radius and apparent size of the planet. Unlike the earlier finding of the rocky planet, this study can provide you a quantitative estimate on how physically big this planet must be. And that turns out to be quite smallar than Saturn. You can also derive the mass of the planet from the scale of the wobble in the main star. Combining that with the physical size of the planet, you can derive the density of the planet.
(*) Kepler's law goes like this:
(2*pi/Period)^2 * (size)^3 = G * Mass
where G = gravitational constant.
If you plug in the Period (==2.87days) and size (0.046AU...circular logic, I know) of the planet, then you'd get the total mass of the star system to be about twice the mass of the Sun, roughly what we expect to be for a G0 main sequence star.
I wish the US would follow other countries with regard to nuclear energy.
Not a f*cking chance. With the word "nuclear" in the subject, the common citizen of the U.S. would simply freak out and protest against buidling such thing. It's already hard enough to educate people around here about the importance of nuclear (fission) technology. What could we do not to scare them even less for something spectacularly energetic machinery like this?
(but then, these are the same people who buy the concept of clean coals...oh yeah, call me flamebait. I can afford the negative karma...)
Non-linearity correction isn't made properly on the satellite image. The satellite image is projected in the tangential plane of the satellite's view, which isn't perpendicular to the surface of the Earth. That results in non-linear grid size and hence the skewness.
why don't they simply adjust it to match for display?
Because these images probably do not come with proper geological coordinate system?
These images are taken from satellite; you need the spatial coordinate of a satellite which took these images, and then reproject it onto the tangential plane, then convert that to non-linear coordinate scheme that the original map uses. These maths aren't too complicated (ok, it will take me days to work out), but getting all the information necessary to perform that conversion may take a while.
Slashdot Mirror
"It doesn't matter how beautiful your theory is, it doesn't matter how smart you are -- if it doesn't agree with experiment, it's wrong." -- R.P. Feynman
I feel that this quote is appropriate, as I believe this type of simulation possibly cannot contain every essential physics that governs the evolution of the Universe. Some oversimplification must be present and some tweaks (e.g. dark matter) may go into the modeling to match whatever we see it today.
This isn't the end of the study of cosmology. That's all I'm trying to say.
It's a possible answer to your question. Look it up!
No,no, you've got the signal wrong. My response was to a part of the parent's submission: "put the wood onto..." Not really thinking about comparison between DI mission vs. Lunar Prospector.
That'd be like comparing an apple and an orange.
[The HST and Chandra are scheduled to monitor this event. Wait & see what will take place then.]
You know that we sort of did this with Lunar Prospector...the HST watched the collision, but didn't see diddly-squat (I saw the data, too).
Ok, strictly speaking the Moon may originate from Earth, so that may not count.
They have determined that the planet does pass in front of the star. Then they went to measure the degree of occultation.
So they don't have to assume it. It's said in the article (from SFSU), I believe.
No luck finding the preprint so far. But here is the thing.
This is a G0 star, so it's likely to have a similar scale size as our Sun. Looking up Simbad, I see that this star is located roughly 80 parsec away, which isn't too far. Now, this new planet. It is 0.72 times the size of Jupiter. So if you take the ratio of apparent discs, it'd be
(pi * (0.72 * 0.7e5km[Jupitar])^2) / (pi * (7.0e5[Sun])^2) ~ 0.005
or 0.5%. So all you need is to achieve +/- 0.1% accuracy in photometry to derive the apparent size...there, easier said than done. No wonder they needed a big telescope to do this accurately.
I think it's doable, though your points are well taken, too. I wouldn't be surprised if there is a factor of two errors.
That's a very good question. I'm glad you are moderated up for that.
I don't think anyone knows for sure what the planet's environment is exactly like. All they can really tell you are that (1) the planet is quite massive and (2) its phyiscal size. The density at the core is implied from it. And whether it has a magnetic field or a moon, that's still up for debate.
I take it that the interpretation of the dataset is not completely unique. There may exist other types of interpretation. And these guys are just throwing in one of theirs to see how the community would react (I'm not one of them, though I submitted the article).
You're not alone in thinking like that. As a matter of fact, you can look back in history and find that, circa 1900, quite a few people shared the same view about the studies of electrons and X-rays as you do today about planets. They thought, "geez, why the hell are we spending on money to study these useless things like electrons and X-rays? What GOOD WOULD THAT EVER DO?"
Now admittedly this may not be exactly the same kind of discovery as electrons. But the idea is the same; we are trying to understand the environment we live in. With hope that will lead us to better and prosperous life in a long run.
If they actually did it regularly, you would expect it.
Readability, sure, but I'm not sure if I want CT to go through submissions and start correcting for spelling...
I see your point, though. Nevertheless, I want to be responsible for my errors and to hold myself to a higher standard.
[Maybe they ought to allow subscribers to proof-read?]
A healthy skepticism is always a Good Thing, I think.
I haven't read the actual journal article, but I'm sure that the paper is accepted by ApJ because error analysis is performed properly. Or so I hope.
Anyway, what distinguishes this work from others (to me) is that many quantitative values (orbital period, the mass and radius of the planet, etc) are measured via observations. That doesn't happen very often in astronomy these days.
Rosetta...I actually checked the spelling but I guess I forgot to correct to that.
I said *I* didn't expect editors to proof-read. If you do (and they don't edit for you), that's a problem between you and editors.
No, the choice of the word "weigh" is intentional.
Key word: little bit. Given that this happening REALLY far away, and we're only observing it through telescopes, it's almost impossible to measure accurately.
We can measure the effect of wobble quite accurately. The current accuracy is about +/- 1 or 2 meters per second. That's usually good enough to detect a planet like this.
But your points are well taken. There are uncertainties to be considered in the analysis. I'm sure these guys did take that into account in their work.
No, grammar and spelling errors are mine, not editors (as I said in the other post).
And I don't expect editors to proof-read, either.
Oh shit. You're right. I didn't catch that one (among other things I goofed in my writing).
To be fair, Zonk didn't edit a thing. It's posted as submitted. So flame me, not editors.
Let me add to that. We know that a G0 star has roughly the same mass as that of our Sun (*). Once you have some handle on its mass, you can do the following:
(1) examine the wobble pattern of the main star,
(2) then examine the effect of occultation (eclipse) by the planet (i.e., when the planet goes in front of the star, the brightness of the star decreases...which gives you a sense on how big this planet is with respect to the star's apparent disc),
(3) then use Kepler's third law to derive the size of its orbit,
Now you have two unique information: the orbital radius and apparent size of the planet. Unlike the earlier finding of the rocky planet, this study can provide you a quantitative estimate on how physically big this planet must be. And that turns out to be quite smallar than Saturn. You can also derive the mass of the planet from the scale of the wobble in the main star. Combining that with the physical size of the planet, you can derive the density of the planet.
(*) Kepler's law goes like this:
(2*pi/Period)^2 * (size)^3 = G * Mass
where G = gravitational constant.
If you plug in the Period (==2.87days) and size (0.046AU...circular logic, I know) of the planet, then you'd get the total mass of the star system to be about twice the mass of the Sun, roughly what we expect to be for a G0 main sequence star.
Think of it as a chance for "do-over" the comment you thought you'd score high mod points earlier...
/hey, subscribers get to see the dupe 30 minutes earlier than you did.
I wish the US would follow other countries with regard to nuclear energy.
Not a f*cking chance. With the word "nuclear" in the subject, the common citizen of the U.S. would simply freak out and protest against buidling such thing. It's already hard enough to educate people around here about the importance of nuclear (fission) technology. What could we do not to scare them even less for something spectacularly energetic machinery like this?
(but then, these are the same people who buy the concept of clean coals...oh yeah, call me flamebait. I can afford the negative karma...)
Meta moderation would take care of this moderator.
Non-linearity correction isn't made properly on the satellite image. The satellite image is projected in the tangential plane of the satellite's view, which isn't perpendicular to the surface of the Earth. That results in non-linear grid size and hence the skewness.
That's all I am saying.
why don't they simply adjust it to match for display?
Because these images probably do not come with proper geological coordinate system?
These images are taken from satellite; you need the spatial coordinate of a satellite which took these images, and then reproject it onto the tangential plane, then convert that to non-linear coordinate scheme that the original map uses. These maths aren't too complicated (ok, it will take me days to work out), but getting all the information necessary to perform that conversion may take a while.
...and now I can see my dad's truck in Japan.
Go here:
STScI Press Release
Click on the top image, then scroll down to find unannotated version of images and click on it. Then you'll find a big TIFF file of this picture.
Enjoy.
Actually, the black pupil isn't really there
Nor those spoke-like features radiating out of the black eye. These patterns are due to the opitical system of the HST/ACS instrument.