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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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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What would happen in this cavern on the Moon?

Imagine a large cavern on the moon, around the theoretical size limit determined by Purdue university - about 1.5 kilometers high, and 5 kilometers across on the floor. This cavern is a kilometer or ...
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How were Mars' zero elevation datum defined? What are their shapes?

Discussions on Boiling ponds and pools on Mars? led me to Wikipedia's Mars; Geography and naming of surface features which says: Because Mars has no oceans and hence no "sea level", a zero-...
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Is there a list of world wide upcoming space events on the web?

Is there a list of all the international upcoming events like launches, expected arrivals at, and landings on celestial bodies, etc. on the internet ?
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Psyche 16 - What will be learned in 2026?

I've been looking into a lot of the Discovery series missions, and came across the fact that 2 future missions are proposed, one for Jupiter Trojans, another for visiting an asteroid named "Psyche 16"...
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What is the heaviest chemical element that has been recovered from beyond cis-lunar space? [closed]

Material has come to Earth from deep space (beyond cis-linar) and been subjected to scientific analysis both in the form of meteorites, and via robotic sample collection spacecraft and robotic ...
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Is planetary impact testing planned for the InSight Mars lander's seismometers?

The question How could InSight's seismometers be intentionally and meaningfully “pinged”? is a hypothetical and has several good speculative answers. But here I'd like to ask specifically about any ...
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Has Mars quaked yet? Any scientific speculation when it might?

We have lots of questions about the Mars lander InSight's seismometers, and I remember reading that they have detected microseisms from wind blowing over InSight's solar panels and the surface of Mars ...
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Dark side of an exoplanet - if it was earth-like would its surface light be detectable?

The Kepler telescope looks at dark sides of exoplanets. If the exoplanet was earth-like would it not have emitted light? Would those lights be detectable, or what technological advances would be ...
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Are there both “lake” and “sea” designations on Titan? Officially or otherwise?

@TomSpilker's excellent answer to How (the heck) do they know some lakes on Titan are 100 meters deep? says at the very end: As far as the lakes (smaller than the seas) go, as the sources you cite ...
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Why exactly would “permanently shadowed polar lunar craters… have substantially higher levels of ³He than sunlit lunar surfaces?”

Researching this answer led to ³He in permanently shadowed lunar polar surfaces published in Icarus. The abstract is tantalizing but terse: Abstract Because of their cryogenic temperatures, analysis ...
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Moon's South Pole-Aitken basin mass anomaly, how to reconcile “isostatic equilibrium” with “heavy metal not sinking”?

The recent Phys.org piece Mass anomaly detected under the moon's largest crater is a review of a recently published and paywalled Geophysical Research Letter Deep Structure of the Lunar South Pole‐...
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How are martian dust devil maps made?

The Gizmodo article A Martian Dust Devil Swept Right Over NASA’s InSight Lander says: What’s unique about this most recent event, however, is that InSight was able to gather other forms of evidence ...
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How tall are Pluto's mountains? Are they the tallest ice features in the Solar System?

The Gizmodo article It Looks Like Pluto Has a Liquid Water Ocean shows a large image of pluto with obliquely lit peaks near both the terminator and the edge of the disk where the topography is really ...
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What materials are naturally released into space from earth?

I am wondering what kinds of materials that are released by Earth into space due to natural processes. If possible, what are their approximate rates in kg per day or year?

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