# Tag Info

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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 rather sparse. Venus's atmosphere appears to contain a small amount of nitrogen when viewed on a percentage basis. "Only" 3.5% of all of the gases in ...

13

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 nitrogen. Even accounting for the Venus surface temperature (~700K vs ~300K on Earth), one still gets more nitrogen mass per volume. Mars: Most of the ...

13

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 is more difficult as the comet is fainter, necessitating a large amount of large (>4m) telescope time which is difficult to obtain. Searching the JPL Small ...

10

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 smaller still and none have been found in the United States. According to the Meteorites in the US page, which draws from the Meteoritical Society database, only ...

10

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 brightness of the banded cloud mostly in the planet's southern hemisphere due to seasonal variations and thus affect overall brightness of the planet. Neptune's ...

9

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, is thought to have a central dense core of 10 to 25 Earth masses that was probably the seed of the formation of the planet, before it ...

8

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 low frequency electromagnetic radiation such as those used by radar. These observations are consistent with a planet that has stagnant lid tectonics and ...

8

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 the pressure is high enough to prevent cave formation. So no for Jupiter, Saturn, Uranus and Neptune. A second requirement is some factor digging cavities. On ...

8

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 the applied tidal field. The Love number is dimensionless, and it encodes information about the body's internal structure. (Poisson et.al., 2009) For Io, the ...

7

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 harder to get a radar return from the very small objects (aerosol droplets or tiny ice particles) that would make up clouds in Saturn's upper atmosphere than it ...

7

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 moon, and ejecta is shot out to all sides. Powerful shock waves push the rock to the side building large walls. As these push down on the edges of the crater, the ...

6

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 kilometers, as opposed to 400,000km for the Moon. So I would say f will be somewhat larger than the moon but not anywhere near what the poster shows. G will appear even ...

6

(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 orbital interactions with planets or moons. Since these interactions will occasionally give enough energy to escape the solar system entirely, presumably anything ...

6

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 many other kinds of surface studies). It is quite substantial in visible light. Probably Clementine data are the oldest-modern reference, and among others, ...

6

$k_2$ 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 Love and Shida numbers exist for each degree of spherical harmonic coefficients. The three Love-Shida numbers for a given degree $n$ are $k_n$, which ...

5

A basic orbital rule is Kepler's third law, which states that the closer the moon is to the planet, the quicker is its orbit. A body that is close to the Earth will move in orbit faster than one which is distant. The fundamental weirdness: If a body is in orbit, and you give it a push in the direction it is moving, it will gain energy, move away from the ...

5

Essentially, it boils down to the question of uniformity. Magellan reached Venus in the early 1990s, and was able to greatly improve on previous mapping attempts. The spacecraft was able to map essentially all of the surface, including the distribution of craters. By measuring the crater density, scientists found that the surface was fairly uniform; given ...

5

Hominids in the neighborhood is probably the biggest mistake made by the artist. Sorry to be a little less optimistic than people at NASA, but a journey this far would probably take hundreds of thousands of years. And we're not in the best condition to prepare for it. The technology needed for such a trip should take time to develop. Too much time, too ...

5

The images you present aren't literal images of Saturn's rings. They're "Doppler-delay" plots: the vertical axis represents distance from Earth, while the horizontal axis represents speed towards or away from Earth. Since the ring particles are moving in circular paths around Saturn, this produces an elliptical chart. Further evidence that this isn't a ...

5

What they have done is take each of the 580 Jupiter-Family Comets (JFCs) from our solar system (from the JPL Small Body DataBase; set object kind=comets, Comet Orbit Classes to Jupiter-family Comet) and kept all of the orbital elements the same, except for the semi-major axis which they have scaled by the ratio of the semi-major axis 55 Cnc d (5.74 au) to ...

5

This might not be so hard after all. Below I show the math for the analytical solution for a Kelperian orbit; the catch is that it's only analytical for $t(\theta)$ and not $\theta(t)$ but that shouldn't cause a problem in this case. I will not solve the problem for you but I'll make a recommendation how to proceed: Step 1: draw a diagram on 2D paper (the ...

4

Neptune and Uranus have estimated core temperatures of 7273 K and 5255 K respectively. Uranus and Neptune however likely do not have liquid water oceans. The combination of pressure and temperature on both planet results in unsuitable conditions for liquid water oceans. In fact for liquid water oceans to form on Neptune, it's predicted it would have to cool ...

4

Interesting question, though probably a better fit for world-building. Firstly "metals" is often used by astronomers to refer to any element other than hydrogen or helium. That is clearly not the intended use here. Terminus has a solid surface at temperatures that humans can stand, and a breathable atmosphere (perhaps after terraforming). So, what can it ...

4

I'm going to approach this question in two steps: what metals are you talking about, and could you have a planet where those metals are not easily extractable. What metals? I get the sense that you're specifically referring to the non-lithophile metals, which include the d-block transition metals iron, nickel, copper and gold, and the chalcophile metals ...

4

If you know for sure and can prove it: write a paper, submit it to Nature or Science. They will accept it and will give you the cover image. We can only look at the planetary interiors superficially. We know the bulk mass, we can do a bit tomography with seismics to determine boundaries in the speed-of-sound, with magnetotelurics in the magnetic and electric ...

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There is a science-based approach to explaining the dark spot on Uranus. In 2009 (the image and sighting of the spot in question are from 2006) a paper was published titled: The Dark Spot in the atmosphere of Uranus in 2006: Discovery, description, and dynamical simulations by H.B. Hammel a, L.A. Sromovsky et. al.. In this work they say that the dark spot is ...

4

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 heliopause, currently at a distance of about 120 AU. (The actual location will change, of course, depending on things like the strength of the solar wind and ...

4

At zeros order such assumption might be made, but a powerlaw relation is more common and accepted. Also a protoplanetary disk is more complex as is the planet formation process which may include radial migration of the protoplanets. So the mass $m(r)$ available at a distance $r$ might not be exactly representative for the planetary mass found at that ...

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