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Questions tagged [planetary-science]

The study of planets, asteroids, comets, etc, including weather, geology, composition, etc. This tag should be used when the focus of the question is on the the science of a non-Earth non-star natural object, and not used when designing spacecraft to cope with said challenges.

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73 votes
5 answers
31k views

Could we breathe an atmosphere that is not nitrogen based?

As I understand it, the important part of Earth's atmosphere that we breathe is the oxygen. However, Earth's air is only about 21% oxygen with the rest made up of about 78% nitrogen and 1% other gases,...
14 votes
9 answers
7k views

How does time work on other planets?

I'm a game developer who makes space-based games. I want to implement a system where the time varies depending on the planet. I think this would work like time zones, but to be honest, I'm not sure ...
6 votes
2 answers
315 views

Is the crust of the Moon different on the near side and the far side?

If you assume that the origin of the Moon is due to an object hitting the Earth. The difference between far side and the near side of the Moon can be explained, if the 'chip' knocked off the Earth to ...
4 votes
1 answer
117 views

Would a ice core samples taken on the Moon provide us with information about the past that we cannot easily obtain in other ways?

This article on NASA's website describes 10 things we’ve learned about Earth by studying the Moon, including the makeup of a newborn Earth and potential clues to how life began on Earth. The ...
4 votes
2 answers
13k views

Does Saturn have a solid surface?

This page argues that Saturn's density tells scientists that it has a liquid metal core with maybe some rocky chunks: The core region of Saturn may never be directly observed. Neither has the ...
2 votes
3 answers
897 views

How can you warm up Mars?

Mars experience extreme temperatures. Highest temperature being 21 degree celsius. So if we are to terraform mars one day then we first need to warm it up. So any ideas on how to warm up mars?
-8 votes
2 answers
146 views

Nuking mars for colonization

While I have seen the idea for nuking Mars’s polar ice caps to release water, the fallout from the thermonuclear blasts could plunge the planet into a nuclear winter which could stop us from ...
22 votes
1 answer
2k views

Could an acid-proof, solar-powered aircraft stay aloft on the sunny side of Venus more-or-less indefinitely?

The length of Venus's solar day is 116.75 earth days ($t$ = 10,087,200 s) and it's radius, $r$, is 6051,800 m, so in theory an aircraft would only need to travel at a ground speed, $s$, of... $$s=2\pi ...
1 vote
0 answers
64 views

Diameters of moons in solar system

I would like to programmatically find all moons in our solar system above a certain diameter. I would like to use the api to jpl horizons if possible. (For context I am then going on to find ...
7 votes
0 answers
116 views

What are the prevailing winds on a tidally locked ocean planet?

I am trying to picture the atmospheric circulation of a tidally locked planet, similar to Earth in mass and atmosphere. The rotational axis would need to be (roughly) perpendicular to the ecliptic if ...
9 votes
2 answers
3k views

Term for deformation due to gravity

In this video, If you look closely, you can see the smaller planet deforming before the actual collision. I think I remember a term existed for this. I think it is ...
14 votes
2 answers
1k views

Does the atmospheric pressure of Mars fluctuate because of the seasonal evaporation of the polar ice caps?

The carbon dioxide ice on the Martian poles are known to evaporate every summer and re-deposit every winter. Where does this carbon dioxide 'go' and does it mean there is a seasonal variation in the ...
20 votes
1 answer
3k views

Why are the Martian poles not covered by dust?

The Martian surface is known to have periodic 'dust storms'. Depictions of Mars typically show poles with ice at the surface. If that is the case why are the Martian poles not blanketed with a thick ...
4 votes
0 answers
61 views

What document describes the scientific benefits of the LRV through an increase in the diversity of rocks returned by Apollo 15-17?

Logically, it makes sense that the rock samples returned by the Apollo 15-17 missions tend to be more diverse than the ones returned by previous missions. The astronauts could reach regions of ...
12 votes
2 answers
566 views

What makes materials on the Moon look so different when the sun is high?

The surface of the Moon looks very different in orbiter images taken at local noon than it does in images from other times. Here are two examples of the same places in Lalande Crater. In each image, ...
0 votes
1 answer
50 views

What is the minimum pressure of a purely CO₂ atmosphere on Europa that can retain enough heat for surface liquid water?

*Ignoring external factors such as Jupiter's magnetosphere blowing this new atmosphere off. I'm not sure where to begin the maths for that
2 votes
1 answer
250 views

Will Enceladus run out of water due to it being lost to space?

The global liquid water subsurface ocean within Enceladus has been identified as being the primary source of material for Saturn's E-ring. Given that the moon is permanently ejecting large quantities ...
23 votes
3 answers
3k views

How does Titan have hydrogen in its atmosphere?

Titan's atmosphere contains few tenths of a percent of hydrogen. This seems odd to me, as Earth with a 4x greater escape velocity cannot retain hydrogen or even helium in its atmosphere. Titan is 3x ...
6 votes
2 answers
257 views

What is the largest possible rocky body? [closed]

Suppose you start with a rocky sphere about 12,742 kilometers in diameter and continuously add more rocky material such that you don't smash this sphere to bits. What is the upper limit for this? ...
38 votes
4 answers
1k views

How deep could a lunar mine go?

Mine shafts on earth are limited in how deep they can go by two things, internal heat and rock pressure. The deepest mine on Earth currently is just under 4 kilometers. There is internal heat on the ...
7 votes
2 answers
255 views

Any additional information required for colonising these rocky solar system bodies?

I am doing some research into the nearby rocky bodies Mars, Venus and the Moon with reference to human colonisation. Are there any specific pieces of information that would be useful to know about ...
13 votes
1 answer
2k views

Is there dirt or its structural equivalent on Mars?

One potential solution to an initial permanent colony on Mars would be a series of modules with dirt floors and walls and slightly convex, transparent roofs. Assuming the interior temperature was ...
35 votes
4 answers
14k views

Could the Moon keep an atmosphere?

When we think of terraforming a body in our galaxy Mars gets lots of consideration as the closest potential body. But what about the Moon? It is currently beyond our ability to add an atmosphere ...
13 votes
1 answer
17k views

If Mars had a denser atmosphere, how warm would it be?

Looking at Venus, Earth and Mars, the closer you are to the Sun the warmer you are. At the same time the warmer planets also have thicker atmospheres. Planet Minimum Maximum Venus 870 °F (465 °C) ...
5 votes
1 answer
85 views

Can waterworld exoplanets have an ocean that's fresh or brackish by terrestrial standards?

The basic system is a terrestrial-type exoplanet in the liquid water zone around a star. The planet has a worldwide, liquid ocean with at most small islands above the surfaceMy question is what the ...
1 vote
1 answer
84 views

Apparent diameter of a planet

I made a simple sheet that based on apparent diameter of a celestial body which shows to me which of my eyepieces I should use to view an object in my telescope. However, some of bodies like planet ...
7 votes
3 answers
7k views

By my calculation the cumulative mass of Mercury, plus Venus, plus Earth's moon, plus Mars, plus Mars' moons, total 99% of Earth's mass. Am I correct?

Does cumulative mass of Mercury, Venus, Earth's moon and Mars total 99% of Earth's mass ?
7 votes
3 answers
544 views

What are the calculations for the time it would take to create a minus 50⁰ C liquid CO2 ocean on Venus by shielding it totally from the Sun?

Cooling down Venus will probably be by far the most efficient method to start terraforming the planet because then you wouldn't have to deal with the high temperatures and pressures at its surface. I'...
18 votes
5 answers
3k views

Feasibility of colonising Ceres?

Ceres is a dwarf planet in the midst of the Asteroid Belt between Mars and Jupiter - its location in the Asteroid Belt makes it a good base to mine the riches believed to exist in the asteroids. ...
6 votes
0 answers
96 views

Is the net electric charge of Venus about 0.01 Coulombs?

A few years ago Venus was measured to be at a surprisingly large electric potential of $\Phi_{Venus}=+10.6$ volts, which may be one of the reasons Venus lost its water. Does this mean that Venus has a ...
5 votes
1 answer
132 views

Titan mountains = downwelling in it's ocean?

Titan, unlike earth has a liquid (mostly) water ocean beneath it's icy crust. (I think) this prevents plate tectonics because it isn't viscous enough to drag the crust with it. The heating of said ...
12 votes
3 answers
518 views

How brightly does Venus's hot surface glow at night? Could you see it? Could you see well enough to walk around?

NASA's Parker Solar Probe Captures its First Images of Venus' Surface in Visible Light, Confirmed links to the new Geophysical Research Letter Parker Solar Probe Imaging of the Night Side of Venus. ...
20 votes
2 answers
125k views

What are the dark areas on the moon?

The Moon has a large number of dark spots, as can be seen on the photo below (Wikipedia), that differ significantly from the lighter areas. The dark areas often seem to be roundish, but not ...
6 votes
1 answer
1k views

Upper limit of human comfort in higher atmospheric pressures?

At what atmospheric pressure, assuming an earth-like atmospheric composition, do humans start to feel uncomfortable? I am not asking for the max survivable pressure, but the point where long term ...
0 votes
0 answers
117 views

Do penitentes predicted on Europa only apply to snow-covered areas and not bare ice?

This answer to What would ice-skating be like on Europa? cautions that it might be difficult because there may be penitentes which Wikipedia explains are snow formations. It links to EarthSky.org's ...
3 votes
1 answer
119 views

Why does Earth's North Pole RA flip by ~180 deg around AD2000 relative to SSB? (JPL Horizons data)

Using JPL's Horizons API I see that the Earth's North Pole RA flipped by ~180 degrees quite suddenly around AD 2000. It was pretty stable around 180deg for at least 1000 years prior, and then remains ...
8 votes
1 answer
315 views

Are we still able to terraform Mars using greenhouse effect?

In the last month, a group from University of Colorado, Boulder, published a paper on Nature Astronomy entitled "Inventory of $CO_2$ available for terraforming Mars", which was highly publicized on ...
5 votes
1 answer
127 views

what is the relevance of ion cyclotron and ion collision frequency ratio

On earth, the ion cyclotron and ion collision frequency ratio is 1 at roughly 118 km, and this is used as one of the definitions of the limit to space. What are ion cyclotron frequency and ion ...
3 votes
1 answer
205 views

Why do two craters in Utopia Planitia look like dark holes and are of the few ones on Mars that look this way?

Screenshot from Mars Trek This enigmatic crater lies in southern Utopia Planitia at 28.72⁰ N, 119.96⁰ E, is about 10 km wide and has a min. height difference between its floor and rim of ca. 1650 m. ...
6 votes
1 answer
92 views

Which were the more than 60 (!) candidate locations for the Mars 2020 rover?

Four years ago I asked for the 21 potential landing sites for the Mars 2020 mission in this question, but now I've learned that there were more than 60 candidate locations ! From NASA Announces ...
5 votes
1 answer
568 views

Why must "Mercury’s core (be) partially molten" to explain its weak magnetism?

EarthSky.org's Top 5 Mercury mysteries that BepiColombo will solve says: Why does Mercury have a magnetic field? Not too many planets have a magnetic field. Among the rocky planets of the inner ...
1 vote
0 answers
63 views

What will be more important for the first NASA led human mission to Mars, the exploration of important science targets or the mining of water ice?

A few months after NASA's decision in November 2018 that Jezero Crater would be the landing site for the Mars 2020 rover mission, the research article The Geology and Astrobiology of McLaughlin Crater,...
6 votes
1 answer
321 views

Depth to diameter ratio of impact craters

Two questions on this site concern themselves with the depth to diameter ratios of craters: Catalog of lunar crater depths and diameters Where on Mars are there possible other collapse features with ...
2 votes
2 answers
199 views

best way to generate electricity on any planet's dark side

What options are available for generating electricity in a space colony if it is at the planet's darkest point all year around without help from nearby outposts?
1 vote
0 answers
97 views

How does the wind behave throughout the day in Jezero Crater? (worried about Ingenuity)

JPL tweet links to mars.nasa.gov's Flying on Mars Is Getting Harder and Harder which explains that seasonal changes are lowering the density of the local atmosphere, presumably due to warmer seasonal ...
28 votes
4 answers
4k views

Do other planets and moons share Earth’s mineral diversity?

Earth is full of different minerals. Each patch of land, between plate tectonics and other forces, finds itself brimming with a variety of interesting and more importantly, different, minerals. Does ...
2 votes
1 answer
143 views

Density vs ocean planet?

According to Nasa.gov: Details: Ocean planets are long imagined but difficult to confirm, and TOI-1452 b is no different. About 70% larger than Earth, and roughly five times as massive, its density ...
3 votes
0 answers
107 views

How far could we see (horizontally), floating inside the acid clouds of Venus at 56 km and at 51 km height above the surface?

Screenshot of Fig. 4 in the article The microphysics of the clouds of Venus: Results of the Pioneer Venus Particle Size Spectrometer Experiment From the Wikipedia section about the troposphere of ...
7 votes
2 answers
294 views

Difference between "mafic floor" and "olivine-bearing floor" in Jezero crater? (Perseverance landing site)

Figure 3: Main geologic units within Jezero crater shown on a basemap constructed from images from the High Resolution Imaging Science Experiment (HiRISE) camera onboard the Mars Reconnaissance ...
7 votes
1 answer
551 views

What would be the challenges for a 50 km long tether to the surface of Venus to get recurrent samples from there?

Basalt fiber would be an excellent material for a tether in the atmosphere of Venus because it could withstand both the acidity and the high temperature near the surface there. From this answer about ...

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