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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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77 votes
3 answers
45k views

What will be the effect if we stand on Jupiter?

As we all know Jupiter is a gaseous gas giant and it has a large mass, almost twice the sum of all other planets in the Solar system. So, if it happens that we go to Jupiter, and, as we know it does ...
SpringLearner's user avatar
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,...
Rozgonyi's user avatar
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51 votes
6 answers
16k views

Is it possible for a moon to have a higher surface gravity than the planet it is attached to?

Is it possible that a moon has a higher surface gravity than its planet? I guess it would mean that the moon has a higher mass, but then it would be the planet gravitating around the moon and the ...
Lucile Bellamy's user avatar
40 votes
4 answers
7k views

If there's nothing special about Pluto, why was it discovered so early?

Pluto was recently re-classified, losing its official status as the ninth planet, because a bunch of other dwarf planets were found in its orbital region that were too numerous and insignificant to ...
Mason Wheeler's user avatar
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 ...
Johnny Robinson's user avatar
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 ...
James Jenkins's user avatar
34 votes
2 answers
44k views

Why is the rotation rate of Venus so slow?

Venus has an extremely slow rotation rate, to the point that it actually rotates slower than it revolves around the sun. In other words, its day is longer than its year. With the exception of Mercury, ...
PearsonArtPhoto's user avatar
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32 votes
2 answers
8k views

Is it true that NASA is hiring a new 'planetary protection officer'?

NASA is hiring a new 'planetary protection officer' to defend Earth from alien matter, and the pay is a six-figure salary: as much as $187,000 a year. When we are not sure whether aliens exist, why ...
goodyzain's user avatar
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29 votes
6 answers
9k views

Why are probes that tend to explore outer system always launched to go outwards instead of straight upwards or downwards?

Let's take a look at the trajectory of variety probe missions. New Horizons and Ultima Thule will be 4.1 billion miles away when it visits the Kuiper Belt object. This chart shows the path of New ...
not_Prince's user avatar
  • 1,507
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 ...
TheEnvironmentalist's user avatar
27 votes
6 answers
6k views

What is the deepest we have penetrated a terrestrial body other than Earth?

Curiosity drills 6.4 cm (2.5 inch) holes on Mars. Comet harpoons have been proposed for future space probes. There are a number of ways in which we can penetrate the surface of terrestrial bodies, but ...
called2voyage's user avatar
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25 votes
4 answers
8k views

When is the next Outer Planet lineup (Voyager)

If I remember correctly, The construction and launch of the Voyager spacecrafts in the early 1970s had an urgency as there was to be an unusual lineup of the outer planets (Jupiter, Saturn, Uranus ...
ICL1901's user avatar
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25 votes
1 answer
5k views

Can I harvest diamonds from the rain of Saturn and Jupiter?

A recent news article on BBC News indicates that 1,000 tonnes of diamonds a year are being created on Saturn This is like science fact that screams it must be Science Fiction! Assuming the ...
James Jenkins's user avatar
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 ...
blademan9999's user avatar
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 ...
phil1008's user avatar
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22 votes
3 answers
3k views

What defines the radius of a ball of gas like Jupiter?

I've seen statements to the effect of: "the gravity on the surface of Jupiter is about 2.5 times that of Earth". The problem with such a statement is that as essentially a ball of gas, Jupiter is not ...
Anthony X's user avatar
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21 votes
4 answers
3k views

Do scientist who study martian geology typically use the term areology?

In the book Red Mars by Kim Stanley Robinson, I came across the word "areology". Is this word often used in scientific publications, or is it a term limited to the scope of science-fiction, ...
usernumber's user avatar
  • 5,068
21 votes
4 answers
11k views

How can Mars have dust storms with such a thin atmosphere?

Mars, as I understand, has a very thin atmosphere. However, it still has weather like this: What causes the thin atmosphere to move fast enough to cause such a monster wave of dust?
user avatar
21 votes
2 answers
6k views

Is water on Mars the same as Earth water?

I would like to know how similar Mars water is to Earth water. Can we survive on Mars with Martian water without any major health issues etc?
goodyzain's user avatar
  • 675
21 votes
3 answers
22k views

Why is the Far Side of the Moon so different from the Near Side?

Here's a photo of the Far Side of the Moon Compare that to the Near Side: Why the difference between the two? The difference is quite significant.
PearsonArtPhoto's user avatar
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20 votes
3 answers
4k views

Why was Titan the first celestial body beyond Mars to be landed on?

If my memories are accurate, then there's only one celestial body beyond Mars, on which any man-made device was landed. Pictures made there are, in fact, quite popular among space fans. But why Titan?...
Zoltán Schmidt's user avatar
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 ...
Duke O's user avatar
  • 341
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 ...
PearsonArtPhoto's user avatar
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19 votes
3 answers
6k views

Did the Mars rovers actually confirm the gravity of Mars?

For years the theoretical calculated gravity of Mars has proliferated science texts and Internet documentation - but did the rover actually do a test to confirm the theoretical gravity is truly equal ...
Chris's user avatar
  • 301
19 votes
2 answers
2k views

Can it be said that Venus is covered by an ocean rather than atmosphere?

At Venusian temperatures and pressures, CO2 becomes supercritical. This means it behaves as a dense liquid yet has no clear upper bound and continuously becomes gas with height. Can we thus say that ...
Anixx's user avatar
  • 3,136
19 votes
3 answers
7k views

How much sunlight gets to the surface of Titan? What would astronauts see?

Saturn being at 10 A.U. means sunlight on Titan's cloud tops is about 1/100 that on Earth's. That's 4000 times the illumination of Earth's moon. Titan's atmosphere is described as opaque smog. If ...
Bob Stein's user avatar
  • 892
18 votes
5 answers
4k views

Is Mohs scale of mineral hardness applicable for rocks and minerals of terrestrial planets other than Earth?

The Mohs scale of mineral hardness is a qualitative ordinal scale characterizing scratch resistance of various minerals through the ability of harder material to scratch softer material. Now there is ...
Nilay Ghosh's user avatar
  • 1,022
18 votes
3 answers
7k views

What is the mysterious "Ball of Mars"?

A recent picture of Curiosity rover depicts a surprisingly accurate sphere on the surface of Mars. What is it, and how is it possible that it is so perfecly spherical? Photo by NASA Mars Science ...
Zoltán Schmidt's user avatar
18 votes
2 answers
3k views

How fast does Roche limit disintegration proceed?

The answers to this question about encounters with Jupiter keep mentioning the Roche limit, inside which solid objects break up due to tidal gravity gradients. Over what time scale does this effect ...
Russell Borogove's user avatar
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. ...
user avatar
18 votes
1 answer
557 views

Why did the Earth based observations of methane on Mars go wrong?

ScienceNews states that: Scientists had previously identified methane on Mars using Earth-based telescopes and spacecraft orbiting the Red Planet. In 2003, researchers detected a ...
Hash's user avatar
  • 18k
17 votes
1 answer
954 views

Is it a pure coincindence that the magnetic poles of Earth are near the geographic poles?

On Earth the magnetic poles are near the geographic poles. Does Earth have this situation by pure luck? What is the situation on other planets?
TheMaskedCucumber's user avatar
16 votes
1 answer
5k views

What causes moonquakes?

Despite having very little geological activity, without any active tectonic plates, the moon is prone to shaking shifts. As far as I know, moonquakes can be caused by the Sun, thermal quakes, or by ...
Manuel Faria's user avatar
16 votes
1 answer
843 views

Would it be possible to "ride the wave" on Venus?

Update: Newly published paper in Nature Geoscience Atmospheric mountain wave generation on Venus and its influence on the solid planet’s rotation rate has open-access links in Science News, ...
uhoh's user avatar
  • 149k
16 votes
2 answers
616 views

How large could Hyperion be and stay porous?

Here is a question originating on the Worldbuilding stack. Hyperion is porous, with a density of 0.55 g/cc; a little more than half that of water. from https://www.space.com/20770-hyperion-moon.html ...
Willk's user avatar
  • 295
15 votes
2 answers
769 views

Is NASA launching fewer interplanetary missions?

We were discussing this in the chat room yesterday, and I thought it might make an interesting question. While missions are lasting longer today than they perhaps ever have, it seems like there are ...
PearsonArtPhoto's user avatar
  • 121k
15 votes
1 answer
1k views

Did the Viking landers detect life on Mars?

The two Viking landers had an experiment on board where they attempted to find life on the planet. The initial results said yes, there was life, but later there were questions raised about the results....
PearsonArtPhoto's user avatar
  • 121k
15 votes
1 answer
3k views

Where to find the best values for standard gravitational parameters of solar system bodies?

Where can I find the best values to use for standard gravitational parameters of solar system bodies for numerical simulation experiments? Here are two sets I've put together. The first set is from ...
uhoh's user avatar
  • 149k
15 votes
2 answers
5k views

How hard is the Lunar surface?

The lunar surface visible to us is mostly regolith - space dust, asteroid remains, and what-not. The true lunar surface is below - at depths ranging from a few inches to a few metres. Given that ...
Everyone's user avatar
  • 13.6k
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 ...
Sebastián García's user avatar
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 ...
Duke O's user avatar
  • 341
14 votes
3 answers
3k views

Did we know the gas planets were truly gaseous before Pioneer 10?

I'm asking for historical scientific knowledge of our understanding of the outer planets, which seems hard to come by. Pioneer 10 was the first probe to an outer planet (Jupiter). Before then, did we ...
DrZ214's user avatar
  • 4,596
14 votes
2 answers
1k views

How tectonically active is Mercury?

Both this article and this paper say that Mercury's tectonic activity is mostly in the past, but the first article does have this to say: After the volcanic activity subsided, the planet has been ...
called2voyage's user avatar
  • 23.7k
14 votes
2 answers
3k views

How will Juno establish existence of solid core within Jupiter and determine its size?

One of the set goals for NASA's New Frontiers Juno mission is studying Jupiter's interior and determining if this gas giant has a solid core and if, how large it is. This is mentioned several times on ...
TildalWave's user avatar
  • 76.1k
14 votes
1 answer
3k views

Can the Sun set twice during the same day on Mercury?

Mercury's day is only a little bit shorter than its orbital period, the relationship is a 3:2 resonance. However, I noticed that the planet's angular velocity at perihelion, 0.265 arc-degrees per ...
SE - stop firing the good guys's user avatar
14 votes
1 answer
2k views

How long will it be light on Venus at night?

The atmosphere of Earth bends light such that there is still light after the sun goes down for a period of time. How would such effects appear on Venus, given the thicker atmosphere?
PearsonArtPhoto's user avatar
  • 121k
14 votes
1 answer
2k views

What is the cause of Saturn's north pole persistent hexagon jet streams?

According to the article on the Cassini Solstice Mission website dating back to December 9, 2009: The six-sided shape remains a mystery. Scientists think the hexagon is a meandering jet stream at ...
TildalWave's user avatar
  • 76.1k
13 votes
3 answers
7k views

What would happen if an Earth-sized body encountered Jupiter?

As we all know Jupiter is a gaseous planet so what would happen if an Earth-sized object happened to encounter Jupiter? Would Jupiter engulf the object and make it stay at Jupiter's core? Would the ...
SpringLearner's user avatar
13 votes
4 answers
5k views

If a gas giant is far enough away from a sun will it freeze solid?

I am reading a book where a gas giant is coming into our solar system. It was a rogue planet, traveling between stars. Given the knowledge we have now, would we expect a gas giant to freeze solid if ...
James Jenkins's user avatar
13 votes
1 answer
2k views

BBC: "In 2009 Prof McDowell & other astronomers performed an experiment in which a similar-sized rocket was crashed into the Moon." Really? Which one?

The line following the title of BBC's Elon Musk SpaceX rocket on collision course with moon reads: A rocket launched by Elon Musk's space exploration company is on course to crash into the Moon and ...
uhoh's user avatar
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