# Tag Info

Accepted

### Why is there so little nitrogen in the Martian and Venusian atmospheres?

Nitrogen, with a molecular mass of 28 atomic mass units, is too light to have remained in Mars's atmosphere. Carbon dioxide, with a molecular mass of 44 amu, could (and does) exist on Mars, but it is ...
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### Why is there so little nitrogen in the Martian and Venusian atmospheres?

3.5% of all atmosphere in Venus still accounts for more partial pressure of nitrogen than on Earth. Venus has ~90bar pressure at the surface, 3.5% of them are ~3.2 bar nitrogen. Earth has only 0.8 bar ...
• 1,770
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### Do some comets spin? If so, how fast?

Yes, comets spin although measuring it can be tricky due to the coma and outgassing from the nucleus. It's easiest to measure the rotation period when the comet is inactive near aphelion although this ...
• 7,135

### Is there a way to tell the difference between earth andesite from Mars

If this is something that you have found (rather than purchased as a meteorite) the chances are very small that it is a meteorite. Even if it is a meteorite, the chances it's a Martian one are even ...
• 7,135
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### How fast is Neptune getting brighter? When was was this first noticed and reported?

TL;DR: There was apparent 11% increase of Neptune brightness during 1980 and 2000. This could be due to multiple reasons. Recent observation suggested the reason to be change in the amount and ...
• 3,226

### Which JWST instrument modes are compatible with observations of the bright trans-Earth planets Mars, Jupiter, and Saturn? Which aren't?

There are approved proposals for Cycle 1 to point the JWST at The Jovian system Jupiter's great red spot Mars Saturn and its moons and rings In those PDFs, they describe exactly what instruments ...

### Do gas giants have a core?

Gas giants are believed to have a solid core. They first formed as icy planets, and were heavy enough to accrete hydrogen and helium from the protoplanetary cloud they were in. Saturn, for instance, ...
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### What is k2, how does it relate to Io's volcanism and how can Juno constrain its value?

It is called Tidal love number. The definition is as follows: In Newtonian gravitational theory, a tidal Love number relates the mass multipole moment created by tidal forces on a spherical body to ...
• 3,226
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### How can it be known that Venus does not have plate tectonics?

There's much less data available from Venus. Some data exists. As mentioned in HDE 226868's answer, maps of Venus's surface exist. Like Earth's atmosphere, Venus's atmosphere is transparent to some ...
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### Caves traced in nine planets of solar system

A key requirement for caves is solid substance: while there may be rock cores inside the giant planets, the rest is liquid or gas. Metallic hydrogen may be solid or liquid in Jupiter, but presumably ...
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### Why is Saturn invisible in this radar image of its rings?

The main issue is that there is relatively little material in Saturn's atmosphere that can efficiently scatter radar waves, so the radar basically just gets absorbed. The key point is that it's much ...
• 14.7k
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### Is the boulder on the peak of Tycho Crater the core of the impactor, or is it a random rock?

It is just a rock. A complex crater like Tycho is formed in several stages as the rock behaves like a fluid. The initial impact completely destroys the impactor and excavates a large cavity in the ...
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### Which JWST instrument modes are compatible with observations of the bright trans-Earth planets Mars, Jupiter, and Saturn? Which aren't?

All modes can be used. But for bright targets, observations are limited to specific filters, subarrays, regions of the target planet, or spectral intervals. James Norwood and colleagues wrote a paper ...
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### How many things are wrong in this "artist view" of the TRAPPIST-1 system?

The 2 big planets are probably f & g and they don't look up to scale to me. While f is the size of Earth, or almost 4 times bigger than the Moon, but it's also further away, ~ 1.3 million ...
• 201
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### Could rocks from Earth have reached the Kuiper belt, or Neptune at least? If so, how?

(I have tracked down the reference that I made in my comment on the question.) Presumably earth rocks once blasted into space (by volcanism or meteorite impact) gain or lose energy primarily by ...
• 2,661

### How long does lunar opposition surge last? Are there measurements of the full Moon getting suddenly brighter?

The lunar opposition surge has been well studied, likely because we can study it in detail, we have surface samples, and so it serves as a baseline for other bodies in the solar system (as it does for ...
• 1,843
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### What is k2, how does it relate to Io's volcanism and how can Juno constrain its value?

$k_2$ is one of three tidal Love-Shida numbers related to how gravitation of another body (Jupiter in this case) changes a planet-like body's second degree spherical harmonics (Io in this case). Three ...
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• 31.4k
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### ...but where did Mars' atmosphere actually GO?

Assuming most of the escaping Martian atmosphere is entrained in the solar wind, it will flow outward until it reaches the termination shock, and then slow down in the heliosheath until it reaches the ...
• 14.7k

### Could a magnetosphere be created for Venus by recreated by spinning-up the planet to a 24 hour day?

Planetary magnetic fields are not produced by their rotation, they are produced by convection in the core. The rotation has an effect on the patterns of convection through Coriolis forces, but is not ...