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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6
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3answers
586 views

How does an atmospheric probe measure temperature during descent?

I heard that the Galileo spacecraft sent Galileo Probe into Jupiter, and it reported temperatures reaching 153 degrees Celsius. The question is, when you send a probe crashing into a planet that has ...
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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 ...
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How much sulphuric acid is on Venus?

According to Wikipedia there are just 150 ppm of sulphur dioxide and 20 ppm of water in Venus' atmosphere. At the same time it is known that there is a considerable amount of sulphuric acid in the ...
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Could the Martian atmosphere, in it's heyday, have caused liquid water in oceanic/sub-oceanic volumes?

Random synapses firing reading across posted questions here on SEx.SE ... Martian gravity is weaker than Terran Martian magnetic field almost non-existent Martian atmosphere is far thinner than ...
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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 ...
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1answer
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What stabilises the axial tilt of planets?

All known bodies of the space rotate around their axis. For example, Earth completes a full rotation cycle in about 24 hours. However, the axial tilt seems to be constant, even though it changes a ...
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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 ...
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1answer
381 views

Is there a system for choosing the Prime Meridian on a given body/world?

According to the answer to this question, the 0° longitude of the Moon is that which points toward Earth. On Earth it goes through Greenwich (although I was amused to hear that the French disagreed), ...
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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 ...
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1answer
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Can spacecraft magnetometers be used in orbits of planets other than Earth?

My lecture slides on spacecraft magnetometers for use in attitude sensing only mention the use in the context of Earth orbits, but leave it open to interpretation if they can be used for attitude ...
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Is the water ice in craters near the moon's poles likely to be accompanied by other volatiles?

Is there enough information to conclude whether or not the water ice in the permanently shaded craters around the poles likely also contains carbon and nitrogen chemicals? (Or any other potentially ...
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1answer
696 views

How strong is the electric charge capacity of Martian dust storms?

In my answer to What would it feel like to be in a Martian dust storm? I assert that Martian dust storms would be best avoided, and as one of the reasons (besides carrying corrosive chemicals like ...
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How strong a magnetic field does Mars need to contain Earth-like atmosphere?

A quick follow-up to How would it be possible to kick start Mars's magnetic field? For example, the Venerean atmosphere is contained by merely an induced magnetic field. How powerful would ...
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1answer
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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?
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How do we measure the atmospheres of Solar system planets?

How much is it possible to measure from Earth and how accurately without sending probes to the planets? I am curious about how atmospheric boundary (altitude), atmospheric pressure, scale height were ...
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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 ...
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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 ...
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Could a planet that is tidal locked to its sun be habitable to naked humans?

It is not an unknown scenario in science fiction; a sun that stays stable in the sky of a planet. Humans (or other sapient species) without space suits battling hot deserts, cold dark night sides, or ...
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Surface material on Saturn's moon Rhea

The Cassini mission has made several flybys of Saturn's second largest moon, Rhea. Do we have any data about that moon's surface geochemistry? I do know there is a thin Oxygen/Carbon Dioxide ...
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318 views

What causes the costs of operating an existing planetary mission?

I read on the Planetery Society blog that it costs USD 25 million this year to maintain the Opportunity rover on Mars and the LRO Lunar orbiter. I would like to see a break down of those budgets. I ...
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What is the barometric formula for a gas giant?

The barometric formula describes the atmospheric pressure depending on height and a host of other things. This formula assumes a constant gravitational acceleration over the whole height of the gas ...
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1answer
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Is there a profile of atmospheric pressure and gravity of Uranus?

One of the intriguing facts about Uranus is that somewhere within the gravity is about 0.9g. Now, if one wants to daydream about living on Uranus in slightly chilly balloons, it would be interesting ...
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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 ...
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Where is the first Lunar soil sample currently located?

During Apollo 11, the first manned lunar landing, a "contingency sample" was taken by Neil Armstrong. From Wikipedia: About seven minutes after stepping onto the Moon's surface, Armstrong collected ...
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1answer
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Are there seasons on Luna?

I saw a comment that made me curious. The Earth's axis tilt is about 23.4°, whereas Luna's is only 1.54°. There is negligible atmosphere on Luna, and as far as I know although signs of water ...
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High resolution images of surfaces of other planets and moons

We have high resolution images of the the surface of the Earth taken by satellites (e.g. the images from Google Earth). Why have none of the orbiters going to any other planet or celestial body in our ...
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1answer
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Is the equatorial mountain range of Iapetus due to cold erosion?

Iapetus, satellite of Saturn, has a huge mountain range along about half its equator. On this list of our solar system's biggest mountains, it is the only entry with uncertain origin. ..The ...
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1answer
656 views

Can a planet or other large body be a superconductor?

From Wikipedia on superconductivity of metallic hydrogen: In 1968, Neil Ashcroft put forward that metallic hydrogen may be a superconductor, up to room temperature (~290 K), far higher than any ...
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1answer
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Is Cassini equipped for detection of non-water-based exobiology?

Looking at one of the latest images of Titan's north pole as taken by Cassini probe made me curious how well equipped this NASA's probe actually is to detect non-water-based exobiology?   &...
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1answer
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Why is the SOI of Jupiter less than that of Neptune?

Recently we had a question on gravitational SOI (Sphere of Influence) of planets but the image in answer has a plot showing that the SOI of Jupiter is less than that of Neptune. However, Jupiter's ...
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1answer
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Is there a significant compositional difference between Oort Cloud comets and Kuiper Belt comets?

Comets can come from two sources, the Oort Cloud, or the Kuiper Belt. Is there a significant compositional difference between the two?
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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. ...
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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.
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Could Jupiter's tidal forces be used to generate energy?

Let's say we have a colony on Europa (or any other Jovian moon really). Jupiter exerts a lot of tidal forces on its satellites. Could this force be used to generate energy for our colonists?
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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 ...
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1answer
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Features on border of a crater & ravine on Mars

This image of the Sirenum Fossae Trough - MGS MOC Release No. MOC2-248 of Mars shows spots on the northern lip of the crater that draw my attention. See the Mars Global Surveyor - Mars Orbiter Camera ...
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1answer
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Any explanation for morphology of within crater formations on the northern Nili Patera caldera of the Syrtis Major volcanic plain of Mars?

The Nili Patera region has enjoyed fairly good media exposure recently, ever since high detail HiRISE (High Resolution Imaging Science Experiment) photographs hit the Internet, showing fabulous sand ...
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1answer
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How can one find the cratering rate for different parts of the Solar System

I've heard that counting impact craters is a great way to figure out how old the surface of a planet is, but I've never heard what the actual rates are. Do they vary from planet to planet? Anything ...
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1answer
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How seriously did astronomers take the idea of a hollow Phobos?

Phobos, the larger moon of Mars, was once theorized to be hollow by Iosif Shklovsky. Plenty of publications reference the idea (such as this snippet from Popular Science), but did anyone take it ...
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1answer
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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 ...
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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, ...
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2answers
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Why are the Rings of Saturn so much brighter than the other planets?

It seems to be a given that gas giants have rings. However,Saturn has rings that are far larger than any others in the Solar System, and far more visible as well. What is unique to Saturn that it has ...
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1answer
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What is responsible for the different colors of Iapetus?

Iapetus, one of the moons of Saturn, is known for having two distinct color regions, one bright and the other dark. This was noted as early as the 17th century. This region can be seen below, and even ...
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1answer
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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?
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1answer
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What causes the cracks on Europa to form?

Europa, moon of Jupiter, has a number of large cracks, as seen below. The cracks appear to be associated with a brownish color, while the base surface appears to be a whitish color. What is the cause ...
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1answer
456 views

What stage of development are meteorology models of Venus?

When the weatherman on TV says 'Rain', I make it a point not to take brolly with me. But jokes apart, meteorology here on Earth is developed enough to assist decision-making. This is demonstrated ...
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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?
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1answer
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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 ...
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1answer
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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 ...
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What caused Cydonia mesas, such as “The Face on Mars”, to be created?

The Cydonia region of Mars is littered with mesas, which are an unusual geographic feature on Mars. A sample of a few of these, including the commonly known as "The Face on Mars", is shown below. How ...