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James Webb Telescope

Darat said:
I don't know why but I had thought the local planets would have been "too bright" i.e. too hot for the Webb to get good images.
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In fact, they are. At least Mars is. The images we got are not even close to the best images we have of Mars.

"Webb's instruments are so sensitive that without special observing techniques, the bright infrared light from Mars is blinding, causing a phenomenon known as detector saturation," NASA's blog post said.

"Astronomers adjusted for Mars' extreme brightness by using very short exposures, measuring only some of the light that hit the detectors, and applying special data analysis techniques."
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Puppycow said:
I concur. Planet 9 may not even exist
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Should be planet 11.

Everyone knows that Pluto was done dirty. Which might lead you to think this should be planet 10. But we have largely forgotten that Ceres was once a planet too, and deserves just as much respect as Pluto.
 
Ziggurat said:
Should be planet 11.

Everyone knows that Pluto was done dirty. Which might lead you to think this should be planet 10. But we have largely forgotten that Ceres was once a planet too, and deserves just as much respect as Pluto.
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Agree on Pluto.
It's got moons so a shoe in for planet status.
I bet it gets brought back soon.
So looking for 10.
 
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Well if you really want to include Ceres, which is smaller than Charon, the moon of Pluto, then I guess we would end up with a lot more planets than just 10 or 11, wouldn't we?

Would our own moon count? It's bigger than Ceres. Also some TNOs. Many other moons of the gas giant planets are also bigger than Ceres.
 
Puppycow said:
Well if you really want to include Ceres, which is smaller than Charon, the moon of Pluto, then I guess we would end up with a lot more planets than just 10 or 11, wouldn't we?
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Yes, we would have more than 11, but not moons.

Would our own moon count? It's bigger than Ceres.
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No, definitely not. This is already settled: Ganymede is larger than Mercury, but it's a moon and not a planet because it orbits a planet. Our moon would not count either, for the same reason. Charon is a closer call since Charon and Pluto orbit a barycenter outside of Pluto, so one could argue that they both orbit each other, but I'd still call it a moon because it's still significantly smaller than Pluto.

Other object like Eris would also be planets, but I'm OK with pushing their numbering past 11, so that the mystery large planet becomes planet 11.
 
Puppycow said:
Well if you really want to include Ceres, which is smaller than Charon, the moon of Pluto, then I guess we would end up with a lot more planets than just 10 or 11, wouldn't we?

Would our own moon count? It's bigger than Ceres. Also some TNOs. Many other moons of the gas giant planets are also bigger than Ceres.
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Why should it matter that there are more than some arbitrarily small number?
 
ThatGuy11200 said:
Why should it matter that there are more than some arbitrarily small number?
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I think his point was that the mystery planet might not end up as planet 11, but as some higher number. But we wouldn't need to order them by orbital radius. In fact, it's probably the wrong way to do it, since then numbers for known planets might change over time as new planets are discovered.
 
ThatGuy11200 said:
Why should it matter that there are more than some arbitrarily small number?
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Ziggurat said:
I think his point was that the mystery planet might not end up as planet 11, but as some higher number. But we wouldn't need to order them by orbital radius. In fact, it's probably the wrong way to do it, since then numbers for known planets might change over time as new planets are discovered.
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Only in the sense that it becomes increasingly difficult to commit all of them to memory.
 
Puppycow said:
Only in the sense that it becomes increasingly difficult to commit all of them to memory.
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That was one of the arguments put forward at the IAU, but I don't understand why that would matter.

Ziggurat said:
It also complicates written records that refer to planet numbering.
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So?

I have training in biological taxonomy. Species names undergo revision frequently. This "complicates written records", but scientists are generally smart enough that it doesn't matter.
 
Puppycow said:
Well if you really want to include Ceres, which is smaller than Charon, the moon of Pluto, then I guess we would end up with a lot more planets than just 10 or 11, wouldn't we?

Would our own moon count? It's bigger than Ceres. Also some TNOs. Many other moons of the gas giant planets are also bigger than Ceres.
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If you want to define a planet as something ball-shaped that orbits the sun we would have hundreds of planets. There are many such objects orbiting at similar distances to Neptune and Pluto or further. That is why Pluto was downgraded.
 
The currently used definition of planet seems to me to be extremely logical and appropriate. I really don't get why some have so much of an issue with it.
 
rjh01 said:
If you want to define a planet as something ball-shaped that orbits the sun we would have hundreds of planets. There are many such objects orbiting at similar distances to Neptune and Pluto or further. That is why Pluto was downgraded.
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That is a beautiful point.
We must look forward to scores of flybys like the Pluto Horizon to prove what an irrelevant object Pluto is. (And of course girlfriend Sharon).

Now back to thread, ..
 
ThatGuy11200 said:
So?
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So it's better to avoid it if there's no good reason not to avoid it. The fact that you can work around a problem isn't an excuse to create it unnecessarily. And really, what does ordering it by radius give you anyways? Once we're including the TNO planets, average radius can be quite different than instantaneous radius, and many of the orbits cross as well, so the ordering of average radius isn't really important or informative. There's no reason to maintain it for those planets in the first place.
 
I'm pretty sure that, if the nature of Pluto and the fact that it was just one of many such objects in a large belt had been understood when it was first discovered, it would never have been classified as a planet in the first place.
 
rjh01 said:
If you want to define a planet as something ball-shaped that orbits the sun we would have hundreds of planets.
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No, not "ball shaped". It's got to be something that's gravitationally shaped into hydrostatic equilibrium. Vesta is "ball shaped", but it's not in hydrostatic equilibrium.

And I don't think we're looking at hundreds, I think we're looking at dozens. But what's wrong with that? Why do we have to cap the number?

And I don't know of a better definition of what counts as a planet. The excuse to downgrade Pluto (not clearing its orbit) doesn't really make sense, because the definition then becomes contingent upon factors other than the object's own properties, and it can change over time in either direction (being promoted to or demoted from planet status) because of what happens elsewhere. Even at its present mass, Jupiter wouldn't have been considered a planet early on in the solar system's history. And if we do find the hypothesized planet 9 (should be 11), it wouldn't be a full fledged planet even at several times Earth's mass if it hasn't cleared its orbit either, which it probably hasn't. I find that ridiculous.
 
Ziggurat said:
No, not "ball shaped". It's got to be something that's gravitationally shaped into hydrostatic equilibrium. Vesta is "ball shaped", but it's not in hydrostatic equilibrium.

And I don't think we're looking at hundreds, I think we're looking at dozens. But what's wrong with that? Why do we have to cap the number?

And I don't know of a better definition of what counts as a planet. The excuse to downgrade Pluto (not clearing its orbit) doesn't really make sense, because the definition then becomes contingent upon factors other than the object's own properties, and it can change over time in either direction (being promoted to or demoted from planet status) because of what happens elsewhere. Even at its present mass, Jupiter wouldn't have been considered a planet early on in the solar system's history. And if we do find the hypothesized planet 9 (should be 11), it wouldn't be a full fledged planet even at several times Earth's mass if it hasn't cleared its orbit either, which it probably hasn't. I find that ridiculous.
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I think 'having cleared it's own orbit' is a perfect definition for a planet. That it may not have applied a loooong time ago or might not again in a far distant future doesn't present me with any issues at all.

A planet is the only thing in it's own orbit that is orbiting the sun. That works for me.

I have never really understood the 'oh, poor Pluto' thing. It's a rock more miles away than can fit into my brain, it doesn't care.
 
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