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Aug
20
comment What decided how the Kepler space telescope was pointed?
I just heard that Kepler was pointed to a field of old stars. Young stars are noisy and harder to find planets at. About 44 minutes into this stressful lecture by David Soderblom, "CfA Colloquium: Stars of an Uncertain Age: The Problem of Determining Stellar Ages".
Aug
19
comment Has SETI data been used for astrophysics? How, or why not?
I'd love to buy an orange in my local supermarket which was picked by SETI. But they haven't found any. I'd pay a little for search for aliens for fun. But not invest anything in it believing that it will improve my TV screen. Why not simply be honest about how unlikelble und ununderstandable the SETI mission is, instead of making up stories about "spin offs"? If SETI does no good to astrophysics, then that's fine. No orange picker hope to find an alien hanging in the tree and use that as a motivation in his salary negotiation with his boss.
Aug
19
comment Has SETI data been used for astrophysics? How, or why not?
No scientific value outside of sociology and psychology, I mean. That Seth Shostak guy indeed sounds as crazy as his deliberate hairdo. If one thinks about it for a bit. Methink he involuntarily inspired that Trump-thing.
Aug
19
comment Has SETI data been used for astrophysics? How, or why not?
So SETI might contribute to technology development, like any random consumer product manufacturer might. But their random data collection has no scientific value? (Unless of course they actually manage to connect with das Funkenalien out there, still waiting). Boinc?
Aug
18
comment What is the difference between gas and dust in astronomy?
The scattering properties makes sense. I've heard that there's a gray zone of "large free molecules" with absorption lines which are difficult to disentangle. In basic school and everyday chemistry gas and dust are pretty distinct, I think. But maybe not so in space?
Aug
18
accepted What is the difference between gas and dust in astronomy?
Aug
17
comment What is the difference between gas and dust in astronomy?
Now you clouded my amateurish attempt to understand this. Monatomic dust? When astronomers casually mention "dust" and "gas", are they maybe just referring to certain wavelengths in their spectrograms? Or are they just waving their hands up there to try to feel what it's like. You have pulled my legs a couple of times before here, @pela, I don't have many more legs left. This is astronomy, you can obviously tell me anything.
Aug
15
comment Motion of the sun as observed from mercury
Indeed, yes, Mercury behaves like that. Thank you for reminding me.
Aug
15
comment Motion of the sun as observed from mercury
That animation starts at aphelion and a surface temperature of -200 C. It ends at aphelion too, but then the temperature is over +100 C.
Aug
14
comment How did the moon's orbit become eccentric?
Luna is in the middle, okay. But Venus is closer to the Sun and still very circular, although tipped over. Mercury and Mars on either side of us, are the most eccentric. It isn't obvious to me how distance to the Sun is correlated with that. Especially since the outer planets are thought to have danced around with each other, but I've never heard of any planet coming close enough to Earth to disturb Luna's eccentricity since its creation. I see no system to this madness.
Aug
14
comment How did the moon's orbit become eccentric?
@userLTK Nix must have the best clock makers in the Solar System, or none at all. :-D
Aug
14
comment How did the moon's orbit become eccentric?
@userLTK Charon has 0.00 eccentricity, I think that supports the idea that it is interaction with n-bodies causes Luna's eccentricity because the nearly single moon Pluto system never gets close to any third gravity well. So early on when the Moon was much nearer, it might have been more circular? Could there be any tendency to orbital resonance of the Moon's orbit, or its orbit's precession, with other planets?
Aug
14
comment Is there some upper limit in the moon size distribution?
Only if it motivates you, of course, I'm just curious. I don't hear much about moon formation, other than Luna which seems to have been an unusual event.
Aug
14
asked How did the moon's orbit become eccentric?
Aug
13
comment Is there some upper limit in the moon size distribution?
Great answer! But you could maybe more directly address the question about why planet mass (1-318 Earth masses), solar distances (1-30 AU) and process (co-formation, impact, capture) all seem to be uncorrelated with maximum moon size in absolute terms. And I've heard that Titan might be a "recently" captured KBO, to explain why it is still outgassing. Is that unlikely?
Aug
12
revised Is there some upper limit in the moon size distribution?
added 47 characters in body
Aug
12
revised Is there some upper limit in the moon size distribution?
Trying to fix my bad English. More edits cause other problems.
Aug
12
asked Is there some upper limit in the moon size distribution?
Aug
12
comment What types of signals is SETI (and other such efforts) looking for?
@NuWin And radio is very practical in space. Just like wheels are on the ground. It is a good idea, but considering our own history and extremely rapid learning about the out-theres, it might soon be history. Just a century ago it was suggested that we light great fires on Earth to communicate visually with the Martians. Every time has its great idea. We fool ourselves if we don't understand what fools we are. Still, it is the best we can do, and maybe those out there aren't better than we are. Contact day: "-So what is the meaning of it all this stuff?" "-We hoped you'd tell us..."
Aug
12
comment What types of signals is SETI (and other such efforts) looking for?
@NuWin I'm afraid radio SETI started almost as soon as we invented radio telescopes. We love our new cool gadgets, and maybe sometimes overestimate what they will achieve. I still think we should listen, but this stuff might be stranger than we can imagine. I don't know of any astrophysical spin offs from SETI. Astronomers seem to be very fussy about what and how and when to observe and don't use any random data.