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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.

25
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2answers
686 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{...
17
votes
3answers
7k 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....
19
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2answers
345 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 ...
31
votes
4answers
5k 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 ...
11
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1answer
1k 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 ...
12
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3answers
1k 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 ...
3
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1answer
5k views

What time and date is the sun directly overhead a given place on Earth?

In different regions, the sun is directly overhead at different times of the year. When do these event happen?
5
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1answer
36 views

Time standard for IERS Bulletin A

IERS Bulletin A and Bulletin B contains Earth orientation parameters. These include the time difference between UT1 and UTC and pole position. The values for these parameters are listed once per day, ...
6
votes
1answer
274 views

What are Ordovican trace fossils, and what do they look like?

There are some unusual structures in recent images from the Mars Curiosity Rover's MAHLI (Mars Hand Lens Imager) shown in the Space.com article Curiosity Rover Spots Weird Tube-Like Structures on Mars....
2
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2answers
82 views

Why is “at least a small tilt” between rotation and magnetic axis required by models of magnetic field formation?

I saw something I don't understand in the Gizmodo article Cassini's First Grand Finale Images Are Stunning—But What Are We Really Looking At?. In a quote of Caltech Professor of Planetary Science ...
5
votes
1answer
173 views

What would a planet's sky look like with different chemical compositions, such as low nitrogen, high methane etc?

What are the processes, chemicals and particles involved in creating colour in a planet's sky? Could you give some examples of sky colour processes different from what happens on Earth?
2
votes
1answer
31 views

Does anyone know a book/article/research that talks about forest fire prevention?

In my college we have to start our thesis in the third semester, so I'm going to do a research about forest fire and its prevention. However, I'm struggling to find a article that talks about that ...
15
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3answers
4k 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?...
6
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3answers
253 views

What are the conditions for an ionosphere to form?

I already asked this on Astronomy SE but did not receive any answer so far: What are the prerequisites for an ionosphere to form? For example, can a planet without any atmosphere have an ionosphere? ...
1
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0answers
31 views

Minimum Surface Water for Plate Tectonics?

There is good evidence that the presence of water on a planet's surface is necessary for that planet to have plate tectonics. My question is this: Do we know if there is a minimum amount of surface ...
8
votes
1answer
168 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 ...
3
votes
2answers
92 views

What would happen if you hypothetically happened to touch an aurora

I think that if you touch an aurora it will give you radiation damage? But then the solar winds at -90C would freeze you, so speaking metaphorically what would happen?
3
votes
2answers
171 views

Would a nuclear explosion over one of the Earth’s magnetic poles momentarily disrupt/weaken the Earth’s magnetic field?

If say the Tsar Bomba had been detonated directly over one of the Earth’s magnetic poles at ground level, would the nuclear electromagnetic pulse generated from that blast have had any momentary ...
8
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4answers
2k 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 ...
1
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0answers
64 views

Would the Gaia hypothesis have any practical use?

I recently stumbled upon the Gaia hypothesis, which briefly states that the Earth itself is a living organism. I am wondering: Would this hypothesis have any practical use? Does it make any ...
6
votes
3answers
346 views

In an Earth-like planet with no history of carbon-based life forms, would there be limestone?

The extent of my understanding of limestone is about what Wikipedia says at the very top of the page: Limestone is a sedimentary rock, composed mainly of skeletal fragments of marine organisms such ...
4
votes
0answers
59 views

Can a cryovolcanic eruption be as powerful as a normal volcanic eruption?

The most powerful volcanic eruption in recorded history was the 1815 eruption of Mount Tambora, an explosion equivalent to 33 billion tons of TNT. Is there any way a cryovolcanic eruption could be as ...
1
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0answers
37 views

How long will it take for plate tectonics to shut down and what will the effects be? [duplicate]

As the interior of the earth cools, presumably there will come a time when the temperature gradient is insufficient to maintain the mantle plumes and hence plate tectonics. How long will this take ...
5
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2answers
126 views

How would a world entirely covered in oceans get the nutrients to support life?

On earth nutrients flow from the land to the ocean. Life on oceans need those nutrients to trive. I was trying to think how an ocean world might support life if there was no land to provide the ...
2
votes
2answers
119 views

How to graph gravity as a function of depth, given radius and density?

I need to do this for a planet that has uniform density, and a planet that has two layers. For the first part, I was given that the density was 550 kg/m³, so I made one column in an Excel spreadsheet ...
3
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0answers
264 views

Puzzle using relative dating principles

This isn't directly looking at a real life ecological example kind of thing, but it requires knowledge of relative dating, so I thought I would come here. Here is what was told: -"Worms" (curved ...
7
votes
1answer
382 views

What “g” would be needed to keep helium on Earth?

I know that helium is a very light and rare gas on Earth because Earths gravity is not strong enough to keep it. Instead, helium and hydrogen are rising through the atmosphere and escape into outer ...
27
votes
2answers
2k 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 ...
17
votes
3answers
28k 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 ...
3
votes
3answers
483 views

Eclipse, Hurricanes, Earthquake…Related Events?

Forgive my ignorance, I'm out of my depth. My wife has pointed to the upsurge climate and geological activity post Eclipse. My immediate response, at least inwardly, was to reject her suspicion. ...
6
votes
2answers
496 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 ...
3
votes
1answer
104 views

Why are storms relatively short on Earth?

From reading articles and the such it is clear that other planets such as Jupiter have storms that lasts months over months. However on Earth, storms last much shorter. In fact, the longest storm was ...
4
votes
0answers
137 views

Did Theia collide directly with proto-Earth?

I was learning about the formation of Earth on Kahn Academy where it was mentioned that a protoplanet named Theia had a glancing impact with the earth and formed the moon. It seems like there is also ...
4
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1answer
170 views

How can scientists measure chemical composition on other planets?

How can scientists measure chemical composition (oxygen, nitrogen etc) and temperature on other planets without being there?
8
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2answers
1k 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 ...
13
votes
6answers
1k 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 ...
10
votes
2answers
17k 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 ...
6
votes
2answers
391 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 ...
0
votes
3answers
502 views

Which physical parameters can we actually measure to confirm the existence of the Greenhouse Effect (GHE)? [closed]

The theory of a GHE in a planetary atmosphere is rather well known. Many claim it is no longer a theory but actually proven as a fact. However I have been reading a lot of things Richard Feynman said ...
8
votes
1answer
332 views

How do tectonics work on other planets?

What kind of tectonic plate activity exists on other planets in the solar system, or even large moons? Are there any deeper studies of what is needed for a planet or large moon to have tectonic ...
21
votes
2answers
5k 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 ...
2
votes
2answers
114 views

Terrestrial Day vs. Venusian Day: Why the Huge Time Difference?

The diameters of Venus (7,520.8 miles) and Earth (7,917.5 miles) are comparable, but the disparity of the length of the day for each planet - as expressed in terrestrial hours - is enormous; a day on ...
2
votes
2answers
379 views

Was there once a glacier over Starcke national park in Queensland Australia?

I was randomly exploring Google Earth when I came across some sort of rock formation in northern Australia. The location of the rock formation with respect to Australia is shown below. It is in or ...
3
votes
2answers
499 views

How long it takes to cool a planet?

Suppose a planet like Earth or Venus is totally isolated from sunlight. How quick would it cool down? On Earth it seems to me that the air temperature drops significantly even during a night. Does it ...
5
votes
2answers
169 views

What is the CI chondrite concentration of REEs/rare metals, in ppm/grams per ton?

I am researching the abundances of rare earth elements and rare metals in meteorite samples, because I want to investigate the notion that asteroids represent abundant stocks of rare resources. The ...
4
votes
1answer
95 views

doubt about the 'white spaces' in the maps from satellite

I have a doubt about the 'white spaces' in the maps from satellite. For example, for the atlantic areas I have plotted AOD and appear many areas where sistematically do not have any data (white spaces)...
34
votes
5answers
3k views

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 ...
8
votes
1answer
135 views

Melting basalt on the lunar surface - what would the resulting material be like?

The idea is to melt the fine-grain portion of basalt regolith using a large Fresnel lens, and let it cool to a solid. The lens would track along a tamped bed of material leaving a molten puddle ...
3
votes
1answer
199 views

How does water still exist on the Earth?

Almost all the theories that explain the origin of Earth says, it was way hot back then. That means It was in a lava state in its early days. Then gradually cooled down to the current state. If ...
4
votes
3answers
615 views

What natural phenomena increase stratospheric ozone?

Most of us know that the ozone layer gets depleted due to green house gasses and other factors. Which made me wonder, is there any natural phenomenon that causes an increase in ozone?