# Tag Info

95

Firstly, Mars has a mean distance from the Sun of 1.524 AU, so by the inverse square law the energy it gets from the Sun is about 40% of what the Earth gets. But the main reason that Mars is so cold is that its atmosphere is very thin compared to Earth's (as well as very dry, see below). From Wikipedia Atmosphere of Mars: The atmosphere of Mars is much ...

27

I'm just going to expand and deepen on what the other answers already said. In the following I contrast the atmospheric transmission ($T$) and absorption ($A$, which is $A=1-T$) of Mars and Earth. The Mars plot (top) is from Prof. J. Irwin via this review by P. Read et al. 2015 and the terrestrial data (bottom) is from wikipedia. The plots of $A$ and $1-T$...

16

Jupiter does not have a "surface" and nor is there anything but an arbitrary division between interplanetary space and where its atmosphere begins. The crushing pressure is its atmospheric pressure. The deeper into the atmosphere you go, the greater the column of gas that lies above you. It is the weight of this column of gas that is responsible for the ...

16

Mars does have a greenhouse effect, only somewhat weaker than Earth's. Mars' atmosphere is very dilute, with a with a surface pressure only 0.6% of Earth's. So even if 95% of it is CO2, that's not a lot. However, it is actually a higher absolute abundance of CO2 molecules than on Earth, which only has a CO2 abundance of 0.04% (by volume; e.g. NOAA, ...

12

I looked at the image and annotated it based on what it most likely is: In black is the formation itself. In blue is a depression underneath it. In grey is part of the boundary of what you believed to be the disappeared half. In green is a ridge to the north. In red are several craters. Here's a more likely hypothesis for what this actually is. The ...

11

They are not real. The images used in the animation use a mosaic of photographs taken by an orbiting satellite, the Clementine orbiter. This satellite has a polar orbit, and so returns images in strips that run roughly north-south. Due to variations in lighting between orbits, when the strips are joined together, there are artefacts at the joins. The ...

7

That's one of the big questions. ESA scientists, at least, think it's worth looking for underground life. See ExoMars mission. More likely than earth worms are microbes, since some microbes on Earth live under similar conditions as presumed for underground Mars.

7

Would an impact event leave visible traces like impact basins, or could the entire surface melt and reform as it is today, as I suppose Earth did when the Moon formed? Could Venus have been a very different planet up until 0.3 billion years ago? How could one find out, what kind of investigation would be needed? Certainly giant impacts were fairly ...

6

The surface of Pluto is not just young, but very young, and also differentiated. The 'heart', Sputnik Planum, may be currently active, with flowing glaciers, and nitrogen snow. This area may have be resurfaced during Pluto's perihelion. Your theory cannot account for the very young age of the surface. Next capture of a rogue planet is not easy. It would ...

5

I don't know, how it works there, but perhaps it is easier to imagine, how it could look. TrES-2b is a gas giant, so it doesn't have a well defined surface. When you are somewhere in the atmosphere then: -When looking up, you will see the light, as deep sea creatures do. The amount of light and its color will depend on how deep you are. -When looking ...

4

Exoplanets are too far away to send satellites or to image them directly. So there is no way to go there and say: there it is a volcano. My guess is that we have to guess from what we know working in the solar system. And we might just get a statistical probability that the planet is active. I would say that there are two cases: If the planet is rocky and ...

4

I would say that your initial observation is flawed, so the question is moot. Huygens landing site, Titan:

4

I'll address WR104 first. The National Geographic article calls it a "potential threat." Yet that potential may be low. There are a slew of articles quoting astronomer Grant Hill on the subject. Hill studied the star and found that it looks like it isn't pointing straight at us. Its axis might be up to 45 degrees in another direction, meaning that ...

4

The average surface temperature on Venus is 462 °C. You would need a temperature above 800 °C before you would notice any light. Added: Here are some calculated radiation outputs of the surface temperature of Venus, a 1000 °C black body and the sun.

4

There are elongated craters from grazing impacts, and these can sometimes get rather odd shapes like Schiller on the Moon and Orcus Patera on Mars (the later is a bit contested, it might have formed from something other than an impact). Double impact craters is another possibility. Some craters occur simultaneously (more direct picture). Splitting impactors ...

4

I'll begin by saying that for exoplanets, the answer to your question is an active area of research, and currently there are no observational constraints on what rocky exoplanets would look like to the human eye. Also, this may be a lot more complicated an answer than what you want for a computer game. If you want to hunt around for this in the ...

4

There's not going to be any surface features. First of all, let's assume you could look through a thick soup of metallic hydrogen. This material has densities starting at that of water, going to the densities of solid rock and even above, while still remaining liquid. On a sidenote: No space probe will ever be able to look into that mess. Only ...

3

The MESSENGER probe was able to take many true-color pictures of Mercury. A full list can be found on JPL's Photojournal. It is clear that Mercury is light grey in color. (source: nasa.gov) (source: nasa.gov) (source: nasa.gov) In terms of the actual surface, Mercury is very similar to the Moon. It's surface is speckled with craters, with some smaller ...

3

The simple answer, unfortunately, is yes. In fact, it is a resounding "yes". Option "A" uses a large "bag" to enclose the asteroid, and then to tow it to lunar orbit (or another feasible location). There's a problem, though, which is that simply surrounding an asteroid with a cylinder won't capture it. You have to "tighten" the "bag". This is implied in a ...

3

I don't know what you're talking about. The only one that seems to have mostly flat rocks is Venus. At least based on what little photographs we have from the surface of Venus. Mars Venus

3

It's a big question, but kind of a favorite subject of mine, thinking about exoplanets, so I can give a ballpark answer, and I invite anyone to give correction or give a more technical answer if they like. Ice(s) formation An ammonia-water ocean wouldn't be friendly towards ice formation because water ice would sink in the ammonia-water solution and ...

2

Comments converted to community wiki Ceres' density (2.08 g/cc) suggests it has abundant water/ice below its presumably mostly dry surface. That and the shiny spot (salts left after subsurface water has sublimated) suggests it wouldn't too difficult. Low gravity, keep the dig in shade to prevent the ice from sublimating in direct sunlight. We could not do ...

2

According to this site, Pluto may experience temperatures of up to 55K, which I assume happens during the daytime. This low temperature is due to Pluto's distance from the sun, its high albedo (about 0.5), and its extremely thin atmosphere.

2

What about the possibility that Venus (and its former moon) went through a much more rapid evolution then occurs normally? Typically a planet-moon system will undergo the following sequence of events: A large object hits the planet and a moon is formed. The planet rapidly tidally locks its moon The moon gradually slows down the rotation of the planet until ...

2

An answer to your question is not known at this time. From the Internal Structure section of Jupiter's Wikipedia page, Jupiter is thought to consist of a dense core with a mixture of elements, a surrounding layer of liquid metallic hydrogen with some helium, and an outer layer predominantly of molecular hydrogen. Beyond this basic outline, there is still ...

1

Most lunar craters are too small to resolve with the naked eye; I would measure a published photograph. A crater near the limb appears as an ellipse whose minor axis is foreshortened but whose major axis measures about the same as if the crater were centrally located. Surface curvature has little effect on this measurement because most craters are small ...

1

The main things to look for are: Decent optics (nearly anything except those with plastic lenses). A steady mount that points where you want to, and moves smoothly. An altitude-azimuth mount is fine because with practice you can guide at high powers. The eyepieces should be 1 1/4 inch size or more expensive 2 inch. The older 0.96 inch are very hard to find. ...

1

In other words, at what hour angle $h$ is the Sun's azimuth $\mathtt{Az}_s$ at a right angle to the wall's normal vector (84$^\circ$ or 264$^\circ$)? Using these formulas, which I've checked, from Wikipedia: Solar azimuth angle, \sin \phi_s = \frac{-\sin h \cos \delta}{\sin \theta_s} \\ \cos \phi_s = \frac{\sin \delta \cos \Phi - \cos h \cos \delta \sin \...

1

Empirically (I fit a regression on log(mass) vs log(surface temp)), using the table of values in the article on Main Sequence stars, I get a fairly well-fitting formula: $\mathrm{estTemp} = 5740*\mathrm{mass}^{0.54}$, where estTemp is in C and mass is in multiples of the sun's mass. Seems to work very well for all but the largest and smallest main sequence ...

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