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Questions tagged [planetary-science]

The multi-disciplinary study of the geomorphology, geology, chemistry, meteorology, oceanography, hydrology, astronomy and astrophysics of the planets and other objects within the solar system.

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36 votes
5 answers
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How do we know the asteroids formed at the same time as earth?

In continuation of the question Why is Earth's age given by dating meteorites rather than its own rocks?, what evidence do we have that the asteroids indeed formed at the same time as earth? Is there ...
Nathaniel Bubis's user avatar
35 votes
5 answers
11k views

How and why did the oceans form on Earth but not on other planets?

Earth is the only planet in our solar system that has copious amounts of water on it. Where did this water come from and why is there so much water on Earth compared to every other planet in the ...
Kenshin's user avatar
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35 votes
1 answer
6k views

What factors determine the number of Hadley cells for a planet?

We know (think?) that Earth has three Hadley cells per hemisphere, but from observing gas giants such as Jupiter, we see that they have many more cells. According to a link from a comment in this ...
congusbongus's user avatar
  • 1,833
28 votes
2 answers
3k views

What sort of climate zones would be present if Earth was tilted like Uranus?

The three main climate zones on Earth are tropics, temperate and polar. Due to Earth's axial tilt, the three zones experience different seasonal patterns: The tropics experience 2 or 4 wet/dry ...
congusbongus's user avatar
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27 votes
2 answers
2k views

Would the Earth function the same spinning the other way?

Right, I saw a question about why the Earth spins counter clockwise, and it reminded me of something I would like to know the answer to. I watched a episode of Futurama. In this episode the Earth ...
Ruddy's user avatar
  • 381
26 votes
2 answers
994 views

Why do some planets have lots of $\mathrm{N_2}$ and others none?

Earth, Titan and Venus all have large amounts of $\mathrm{N_2}$ in their atmospheres. (In the case of Venus it's a small proportion, but Venus' atmosphere is very thick, and the total mass of $\mathrm{...
N. Virgo's user avatar
  • 1,602
23 votes
2 answers
495 views

What properties must a rocky body possess in order to exhibit plate tectonics?

The Earth exhibits plate tectonics, but the other terrestrial planets do not (though Mars and Venus may have exhibited plate tectonics in the past). What is "special" about Earth that allows it to ...
senshin's user avatar
  • 1,885
23 votes
1 answer
3k views

Why do Earth and Venus have different atmospheres?

Venus appears to be the closest to Earth in mass, density, size, etc. - though they clearly have different atmospheres. Why do Earth and Venus have different atmospheres?
blunders's user avatar
  • 4,601
22 votes
2 answers
981 views

Is there geological evidence that the moon once collided with the Earth?

I've seen models in astronomy that show how the Earth-Moon system must have come together after a collision. However, I have not heard whether there is any actual physical evidence on Earth that ...
f.thorpe's user avatar
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22 votes
2 answers
10k views

Plate Tectonics: Is it possible to have an ocean-continent divergent boundary

I am procedurally generating planets for an open world space sandbox game. I am using a rough simulation of tectonic plates to create mountain ranges and other geological features. A planet surface ...
Jacques Nel's user avatar
20 votes
4 answers
17k views

Will the Earth ever stop rotating?

It is well known that the Earth's rotation is slowing down and that millions of years ago there was a point in time where there was only a mere 20 hours in a day on Earth. My question is in two parts....
Kenshin's user avatar
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19 votes
2 answers
651 views

To what accuracy and precision do we know the volume of the Earth?

Satellites such as GOCE and GRACE measure the geoid with unprecedented accuracy. Altimeters can determine local surface elevation with millimetre-precision. This makes me wonder: to what precision ...
gerrit's user avatar
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19 votes
1 answer
1k views

Can Venus be considered to be tectonically active?

Venus is noted for its absence of spreading ridges, transform faults, and subduction zones, which are characteristic of plate tectonics on Earth. But given that it exhibits rift zones, mountain belts ...
decvalts's user avatar
  • 1,817
18 votes
3 answers
39k views

Why does the earth spin clockwise?

Why does earth rotate in a clockwise direction? Did a large meteor collide with earth causing earth to rotate? If that is what happened, could another, larger meteor cause earth to reverse its ...
tux's user avatar
  • 1,662
18 votes
3 answers
5k views

Is there any evidence for higher air pressures in the geological past?

I was curious about how the Earth's overall air pressure has varied over time, and tried to take a look around the internet. However, Google pops up a lot of sites with questionable science proposing ...
kingledion's user avatar
  • 3,376
16 votes
1 answer
519 views

How much silicon is in the Earth's core, and how did it get there?

With some informal conversation with a peer of mine, he had suggested that there is evidence (which he couldn't find,but had remembered reading) that there was Silicon in the Earth's core. I referred ...
Neo's user avatar
  • 6,456
15 votes
5 answers
3k views

Is Earth an organism?

According to Wikipedia, "all known types of organism are capable of some degree of response to stimuli, reproduction, growth and development and self-regulation via homeostasis." Further, watching a ...
blunders's user avatar
  • 4,601
15 votes
3 answers
5k views

Do other terrestrial planets have "earthquakes"?

I know some planets have storms akin to what we have on Earth although obviously varying in nature. I was wondering if other planets have earthquakes? Since this comes down to plate tectonics (right?...
Stan Shunpike's user avatar
14 votes
2 answers
3k views

Earth's ocean basins

Was Earth's sea-floor always carved with the numerous geological features that we see today, or was it at some point flat and boring as Mars is today?
Lucian09474's user avatar
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14 votes
1 answer
383 views

What is this strange feature on Mars in Valles Marineris

While I was browsing Mars on Google Earth, I stumbled upon an interesting feature on one of the slopes of Valles Marineris. The feature seems unique in the sense that I couldn't find any similar ...
Tony's user avatar
  • 141
14 votes
1 answer
199 views

What kinds of remote sensing required to observe methanogenic life on Titan?

Inspired by Chris McKay's Possibilities for methanogenic life in liquid methane on the surface of Titan. In the paper, the PI's found that the consumed acetylene, ethane, and other organic solids ...
Neo's user avatar
  • 6,456
13 votes
6 answers
2k views

Are there any photographs of mountains without significant erosion (on Earth or otherwise)

I'm curious about how mountains on an airless world such as the Moon would look if you were standing on the surface and looking at them. There are plenty of artists' impressions, of course, but I'm ...
N. Virgo's user avatar
  • 1,602
13 votes
1 answer
637 views

Will dust storms be more frequent in the future?

I noticed that in some science fiction movies set in the future on Earth, like Wall-E and Interstellar, dust storms are very prominent. Are there any scientific hypotheses suggesting that dust storms ...
Aryaman Bansal's user avatar
13 votes
1 answer
275 views

Why does Mars' experience an 'ice age' at high axis obliquity, when Earth experiences an ice age at low axis obliquity

This paper here goes into some detail about how Mars' experiences its own form of 'ice ages' on a quasi periodic basis driven by the wobbling of its axis. The main mechanism outlined is that the ...
AlexLipp's user avatar
  • 1,715
13 votes
1 answer
254 views

Phase changes deep in planetary interiors and their implications for surface tectonics

Earth's core mantle boundary represents a phase change from a solid (though convecting) mantle to a liquid Iron/Nickel core. This dramatic transition is likely the origin of the D" boundary, as well ...
Neo's user avatar
  • 6,456
13 votes
1 answer
561 views

Did Jupiter really make Earth (in)habitable?

A new study by Batygyin and Laughlin suggest that a Jupiter migration toward the inner region of the Solar System during the early stages of system formation cleared the habitable region (Goldilocks ...
arkaia's user avatar
  • 15.5k
13 votes
1 answer
315 views

Is Mars' mantle homogeneous or heterogeneous and what might this say about mantle convection?

A supervisor of mine made an off-hand comment about the fact that Mars used to have plate tectonics, and there is evidence that Mars used to have plate tectonics, however now it does not. The theory ...
AlexLipp's user avatar
  • 1,715
12 votes
1 answer
2k views

What is the fastest the Earth has ever spun?

How fast can the Earth rotate and support life? In prehistoric times, dinosaurs were so massive that archeologists wonder how they were not crushed under their own weight. Could a faster spinning ...
Muze's user avatar
  • 1
12 votes
2 answers
2k views

Geomorphology of Mountains With Wind only Erosion

I am curious what mountains would look like if erosion occurred almost entirely by wind. Specifically, I am curious of how granite mountains would look on a "snowball" terrestrial-sized xenoplanet. ...
TechZen's user avatar
  • 571
12 votes
2 answers
228 views

Mechanism for Pluto's young surface

According to recent reports (e.g. in Nature), Pluto is geologically active. It has some mechanism by which it has "recycled" its surface. I originally thought we had a similar case to Jupiter's moon ...
Lucian09474's user avatar
  • 1,942
12 votes
1 answer
741 views

What causes "shallow" moonquakes?

It is thought that "deep" moonquakes are caused by tidal forces exerted on the Moon by the Earth and Sun. Some other sorts of moonquakes are thought to be caused by impacts, or by thermal expansion (...
senshin's user avatar
  • 1,885
11 votes
2 answers
244 views

Why are impact craters radially symmetric?

Okay, so I believe that most of the impact/collisions happen at oblique angles to the planet's radial direction. (I am not very sure about this, but since it is not a freefall, we can assume that the ...
Prithvi Thakur's user avatar
11 votes
2 answers
253 views

What oxidised the soil on Mars?

What exactly was it in the ancient Martian atmosphere that made it red? Was it water, molecular oxygen or something else?
Andykins 's user avatar
11 votes
1 answer
838 views

Does the global temperature vary daily (hotter and colder days)?

Earth's current average global temperature (i.e. including hot deserts and cold polar caps) is reported be somewhere between 14°C and 16°C (depending on sources and methods). This temperature varies ...
summerrain's user avatar
11 votes
5 answers
6k views

Carbon dioxide on Mars, Venus and Earth

Earth's atmosphere is 0.038% carbon dioxide. Mars's atmosphere is 95.3% carbon dioxide. Venus's atmosphere is 96.5% carbon dioxide. If Earth's climate is controlled by CO2, then why is Mars so cold ...
Lucian09474's user avatar
  • 1,942
11 votes
1 answer
137 views

Does the Sun's oscillation affect Earth's climate?

Today, discourse on climate change seemingly tends to focus on earthly elements such as pollution and human activity. While I am certainly not well-read on climate change research, after inspiration ...
mnml's user avatar
  • 111
10 votes
1 answer
3k views

What color(s) would Earth be without water or life?

Many of the celestial bodies in our solar system have well-established color schemes, at least in the minds of the public. Mars is pale-red and black, Venus (beneath the clouds) is generally shown in ...
Nerrolken's user avatar
  • 333
10 votes
1 answer
141 views

What properties must a rocky body possess in order to exhibit the magnetic dynamo?

The magnetic field of the Earth is produced by the magnetic dynamo. What conditions must a rocky body possess in order to exhibit the dynamo? Clearly, the planet's interior must not be too cold. ...
Irigi's user avatar
  • 573
10 votes
1 answer
289 views

'Late Veneer' on other planets

Is there any evidence of external material source events, like the 'Late Veneer' on other planets? Or is this theory specific just for Earth? Note, that this question may be related to How and why ...
Neo's user avatar
  • 6,456
10 votes
1 answer
325 views

How would weather change on a tidally-locked terrestrial planet?

On Earth, weather is very much affected by the Earth's rotation around its axis and around the Sun. Even locations that are almost on the equator do have strong annual variations in precipitation and ...
Irigi's user avatar
  • 573
9 votes
3 answers
721 views

How bad is geo-engineering?

It is just curiosity that forced me to ask this question. At some point in time, if we can't control global $\sf{CO_2}$ emissions, temperature will increase until a tipping point and it will be a ...
Gemechu Fanta Garuma's user avatar
9 votes
2 answers
24k views

How does the Sun heat the Earth?

The core of the sun has a temperature of 15,000,000 °C. The surface of the sun has temperature around 5,000 °C. The sun is around 93 million miles (150 million km) away from earth. My Question: With ...
PCmedia's user avatar
  • 113
9 votes
1 answer
351 views

What sort of instruments do planetary geologists use to predict that there are oceans on the moons Titan and Europa?

NASA Planetary Scientists released a video that says they have confirmed that there is an underground ocean in Europa and that Titan has liquid oceans made of hydrocarbons. I myself am an aspiring ...
Lucian09474's user avatar
  • 1,942
9 votes
1 answer
221 views

What is the current status of geophysical global cooling theory?

Plate tectonics effectively rubbished the theory of geophysical global cooling as a means of explaining many surface features on the Earth. However, this wiki says that the same process is responsible ...
christopherlovell's user avatar
9 votes
3 answers
2k views

What are the criteria that make a planet (in)habitable?

Recently, I realized a lot of factors must contribute toward making a planet habitable, other than just the ones that come to mind like having oxygen, the right temperature, and so on. What makes a ...
Stan Shunpike's user avatar
9 votes
2 answers
482 views

Impact craters vs volcanic explosions on Mars

A maar is a shallow volcanic crater with steep sides that is surrounded by tephra deposits. The tephra deposits are thickest near the crater and decrease with distance from the crater. Source: http://...
Lucian09474's user avatar
  • 1,942
8 votes
3 answers
541 views

How do archaeologists address time dilation when analyzing carbon dating results?

It is a proven fact that the gravitational force exerted upon an object directly affects that objects experience of time; the greater the gravity, the slower time passes, and visa versa. While the ...
AdrianBakker's user avatar
8 votes
2 answers
3k views

How far up do you have to go before most of the atmosphere is below you?

If I wanted to make an air shield around the earth to contain exactly half the planet's atmosphere (by mass), how far above sea level would I have to build it? It's slightly complicated to me because ...
xaxxon's user avatar
  • 183
8 votes
2 answers
599 views

Are old geophysics textbooks useful?

I have had much success with old textbooks in mathematics. Generally, for any branch of mathematics that I (as a non-mathematician) would like to learn or re-learn, I can buy a classic textbook from ...
kingledion's user avatar
  • 3,376
8 votes
2 answers
519 views

Is it possible for tsunamis to occur on deep water planets?

Assume a water planet with an ocean depth of about 200-500 km. Would a very strong ground-quake happening at the very bottom of the planet's ocean floor be able to cause a large tsunami to rise up to ...
ZanMoon-chan's user avatar