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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Still trying to understand “knee” in Earth's atmosphere >100 km; if pure Ne or Ar would it still be there when MFP exceeded scale height?

There is currently one answer to How many solar system bodies have "knees" in their atmospheres? that points out that somewhere above roughly 100 km turbulent mixing drops off (thus the name ...
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How many solar system bodies have “knees” in their atmospheres?

Discussion lead to citing Why does Earth's atmospheric density have a big "knee" around 100 km? Is there a good analytical approximation? who's answer is "monatomic oxygen". ...
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Surface processes of the valleys on Mars

I have two related questions about geophysical processes related to talus* fans on Mars: How were talus fans on Mars formed? (like Valles Marineris or Kasei Valles) What is the role of these fans or ...
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Could we intentionally contaminate another celestial body with life to start producing oxygen?

My question is simple, could we "nuke" a planet with life to create an atmosphere over time? I was seeing a documentary about Jupiter's moon, Europa, and how it could have hydro thermal ...
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Use of VLF to create a Mars barrier

I just ran across some older articles in 2017 discussing how VLF radio waves created an artificial barrier to space weather. Basically how VLF improves Earth’s protection from solar radiation. This ...
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The Surface of Mars

There are surface features on Mars that we can observe with remote sensing data. There are many shorelines seen in a way. Despite its subtle atmosphere or storms, these surface features remain. How do ...
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Which of the four inner planets has the strongest magnetic field, Mars, Mercury, Venus, or Earth?

Which of the four terrestrial planets has the strongest magnetic field, Mars, Mercury, Venus, or Earth?
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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 ...
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When and where on Planet Mars are the Sun's rays the most blueshifted?

Let's say for a moment that the spin of a planet causes the Sun's rays to be blue-shifted in the morning. As far as I know, redshift occurs in steps of like 2.6 km/s or something like that. We can't ...
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How to determine the distance between Olympus Mons and Valles Marineris?

How can I determine the distance between Olympus Mons and the closest point of Valles Marineris? What tools are available to the general public for these kinds of queries?
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How hard is the hardest ice in the solar system? Is it in Pluto's ice mountains?

NPR's Pluto Has White-Capped Mountains, But Not Because There's Snow includes the following: "Initially, it seemed logical that this high-altitude frost could form like on the Earth," says ...
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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 ...
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Updating of TAI

In spaceflight keeping track of time between systems widely separated in space (e.g. people on Earth vs spacecraft in deep space) and/or time, moving at substantial relative velocities and in ...
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Is the surface environment of Venus corrosive?

Venus famously has clouds of concentrated sulfuric acid in its upper atmosphere. Frequently I will see posts here citing the acidity of the atmosphere as a challenge to probes on the surface (such as &...
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What is “Planetary Defense”, and what are the threats one can potentially defend against?

The planetary-defense tag has the current (my) awkwardly-written description. related to the defense of a planet from a major destructive event such as an impact, or searches for or studies of ...
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Obtaining Europa's samples from Callisto. Possible to identify them? Worthwhile?

A lot has been discussed about the possibility of panspermia between Earth and Mars, and how compact systems such as Trappist-1 can be more prone to that. Here on Earth, we have identified numerous ...
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Using Venus' Atmosphere to Cool the Earth [closed]

The Starfish Prime nuclear test on July 9, 1962 caused massive fluctuations and degradation of the Earth's magnetic field. This field is largely responsible for redirecting the Sun's solar radiation. ...
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Roughly express how much of our Moon's apparent libration amplitude seen from the Geocenter is due to different effects?

My understanding is that when tidal locking of a body first happens it transitions from a state where the average rotation period is faster than the orbital period to a state where they are the same ...
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Is Earth's “pear shape” mostly J₃?

@OrganicMarble's answer to 1959 Peanuts cartoon about the Fischer ellipsoid (Earth is “pear-shaped”)? finally let me see the cartoon that Mathematician, Engineer and Geoscientist Irene Fischer wrote ...
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How “locked” are Pluto and Charon? How much does each librate as seen from the other?

Discussion below Are all or some geostationary satellites tidally locked to the Earth? got me thinking about Pluto and Charon. According to Wikipedia: Charon and Pluto orbit each other every 6.387 ...
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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, ...
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Would there be snow, rain, fog or clouds in a deep, sealed, subsurface cavern on the Moon if water were present?

The question Most efficient method of storing energy with water on the moon? proposes a several hundred meeter tall subsurface cavern on the Moon. I added the following comment to an answer: I keep ...
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Possible explanations to a negative correlation between iron (Ferromagnetic) and magnetic field observations from orbit

When looking at magnetic field observation of a planet with no current magnetic field, we can observe magnetic anomalies, which is basically when ferromagnetic minerals acquire remanent magnetization ...
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What radio signals have NASA transmitted to outside our solar system?

What radio signal have NASA transmitted to outside our solar system and what did they contain?
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Is there an European Space Agency's innovative advanced concept program?

I would like to know if there's an equivalent to NASA's NIAC at ESA. If that's the case, I would like to know if I can read some of these concept studies and what stages of approval they need.
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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 ...
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How does time work on other planets?

I’m a game developer making a space-based game. I want to implement a system where the time is different depending on the planet. I think this would work like time zones, but to be honest, I’m not ...
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How does a planet's gravity push away smaller bodies that would otherwise intersect its orbit?

I was reading an article about dwarf planets online where I stumbled upon the following definition of a planet: The International Astronomical Union defines a planet as being in orbit around the ...
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What was Steve? Is it called something else now?

"Steve" was a temporary name for a space phenomenon above the Earth. Since then it's likely much work as been done and a more permanent name chosen. So I'd like to ask what Steve really was/is, and if ...
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What is the slope of the sides of Aristarchus crater on the Moon?

The question If you fell into a crater on the moon in your spacesuit and no jetpack, is there a way to use low gravity to get out of the hole? mentions Aristarchus crater as an example. It's a pretty ...
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Lunar surface illumination levels

I am trying to determine the lunar surface near or far side daytime illumination levels in Lux or foot-candles but there seems to be no directly measured values available. I did find this information ...
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How many times were things crashed into the Moon “for science” (seismic events)?

This answer to Did Apollo 13 produce any scientific results? begins: In addition to crashing the Saturn V's S-IVB into the moon to collect seismic data from sensors installed by the crews of Apollo ...
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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 ...
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Are there any preliminary results from Mars lander InSight's RISE antennas?

@karthikeyan's excellent answer links to The Rotation and Interior Structure Experiment on the InSight Mission to Mars (Folkner, W.M., Dehant, V., Le Maistre, S. et al. Space Sci Rev (2018) 214: 100. ...
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Is the sunlight reflected off of either the atmosphere or surface of a planet polarized?

Is the reflecting off of the surface of the terrestrial planets (those with or without an atmosphere), or the gas- or ice-giants, polarized, or unpolarized like the sunlight before it is reflected?
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Underground sea in Titan, is it water or hydrocarbons?

The truth is that I have read a lot and I have become confused, the underground sea that Titan has, is it water or hydrocarbons, is anyone certain?
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Most likely future sample return missions?

Please bear in mind I have very little space/astronomy knowledge with any comments or answers but I am curious and quite keen to learn. Aside from Mars itself as that is such a likely candidate, what ...
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Can mineralogy maps be made without dedicated instruments? MAGIC at Callisto

While we are still waiting for the official Discovery finalists announcement, and it's perhaps a bit premature to be discussing the proposals, I've been thinking about the exciting MAGIC mission to ...
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Are Mars' atmospheric CO₂, O₂ and CO in equilibrium? Are sunlight or chemical reactions involved?

According to the NASA JPL video linked below the top five gases comprising the martian atmosphere include CO₂, O₂ and CO. Do the proportions reflect some chemical equilibrium? Are sunlight or chemical ...
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How does composition change if you extend an Earthlike atmosphere 50km below sea level? [closed]

I'm working to design a fictional planet inspired by Venus (let's call it Cael). At an altitude of 50 km, Cael's atmosphere is essentially identical to Earth's atmosphere at sea level, and parallels ...
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Acoustics in Space

Acoustics is an important aspect of not just our architecture but how we and other deep ocean creature interact with each other and the surface. It is known to be used in submarines and other research ...
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What would be the challenges for a 50 km long tether to the surface of Venus to get recurrent surface samples 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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What does “clumps and streams” of hydrogen leaving Mars' atmosphere really mean? Are there images of them?

This excellent answer to Just how huge is Mars' cloud of hydrogen? links to the 14 October 2014 Nature News item "Hydrogen Cloud Blows Off Mars", by Alexandra Witze, https://www.nature.com/...
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How are marsquake epicenters determined using only one seismometer?

This tweet says: Cerberus Fossae is the first active seismic zone ever discovered on Mars. Located about 1,600 kilometers east of @NASAInSight lander, this huge extensive tectonic structure was the ...
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Just how huge is Mars' cloud of hydrogen?

NASA Goddard's July 2018 press release NASA’s MAVEN Spacecraft Finds That “Stolen” Electrons Enable Unusual Aurora on Mars says: But two puzzles make this type of aurora seem impossible at first ...
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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 ...
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Is the retrograde (clockwise) rotation rate of Venus speeding up or slowing down?

In the update of the question "Would it be possible to "ride the wave" on Venus ?" there are links to articles in Science and in Science News that report that the atmosphere of Venus, hitting the ...
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Which scientific articles together give proof of all the chemical elements found on Mars?

Wikipedia about the elemental composition of Mars: Based on these data sources, scientists think that the most abundant chemical elements in the Martian crust, besides silicon and oxygen, are iron, ...
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Is it possible to force atmosphere onto a non atmospheric planet?

If you had some way of injecting large masses of gas into a small planets gravitational field, would it form an atmosphere? You would have to pump it at an extreme rate but would it still work if the ...
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Have gravitation multipoles of Jupiter and Saturn beyond J2 been measured or at least estimated? At least the zonal harmonics?

This excellent answer has me wondering if there are any measurements or estimates of gravitational multipole moments of Jupiter or Saturn beyond J2. Here is what I found for J2 (in unitless form) in ...

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