Questions tagged [moons]
Questions about celestial bodies that orbit another celestial body.
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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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Why do artificial satellites need orbit correction, but natural ones don't?
No matter how much you fine-tune a satellite's orbit up front, it needs periodic adjustments. It's usually done through tiny rocket bursts. The system and fuel to do that costs money and weight, and, ...
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Have any of the rovers ever recorded a solar eclipse on Mars?
I've heard a rumor that Curiosity rover sent a recording about Phobos covering the Sun on the Martian sky. Did it happen? If yes, how frequently could such things be recorded?
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Are all satellites of all planets in the same plane?
I'm aware of the fact that all planets are almost in the same plane as the Sun and the Earth(ecliptic) plane except Mercury and Pluto(which are more tilted). Are all satellites of all the planets also ...
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Can a moon orbit its planet faster than its planet rotates?
Can a moon orbit its planet faster than its planet rotates?
Can a moon orbit its planet more than once per the planet's day? It seems possible but I'm not sure.
Are there any known examples of this ...
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Escaping moons conflict with what I understand of gravity
I have known that the Earth's Moon, let's call it Luna (tip of the hat to The Expanse), has been slowly but surely increasing it's distance from the Earth by a small measure each year.
This week I ...
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If colonists burrowed far enough under the ice on Ganymede or Europa, would the ice provide adequate protection for them from Jupiter's radiation?
This is a hypothetical question I'm asking as a SF writer, and the time setting would be approximately 2,250 AD.
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How large could Hyperion be and stay porous?
Here is a question originating on the Worldbuilding stack.
Hyperion is porous, with a density of 0.55 g/cc; a little more than half that of water.
from https://www.space.com/20770-hyperion-moon.html
...
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Would it be possible to "fall off" Phobos? [closed]
Phobos (one of Mars' moons) has the following dimensions: 27 × 22 × 18 km. It has low mass, and little or no gravity/atmosphere.
Let's just assume that it's possible to walk around on Phobos without ...
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Why are sections of Cassini photographs blurred?
In this photograph of Rhea, taken by the Cassini orbiter, there are sections near the terminator that are very blurred, a stark contrast from the crisp sharpness of the rest of the image. The blurred ...
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Is there a term to refer to a planet and its accompanying moons as a whole collection?
I am trying to find out of there is a term that can be used when referring to both a planet and any accompanying moons (if present) as a whole collection. For example if you were to refer to Mars and ...
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Is it possible for moons to have their own moons?
I'm wondering, if it's possible for moons to have their own natural satellites, something big enough to be spherical? Stars have planets, planets have moons. Is it possible that moons have moons too?
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Pluto's satellites other than Charon orbits around Pluto or center of gravity between Pluto and Charon?
As the center of gravity between Pluto and Charon is outside Pluto does Pluto's satellites other than Charon such as Nix, Hydra, Kerberos or Styx orbits around Pluto or the COG?
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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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Did the spacecrafts Galileo or Juno use the Galilean moons for a gravity assist before entering Jovian orbit?
Galileo and Juno are the only two spacecraft to have entered orbit around Jupiter.
Did either of them use one of the Galilean moons for a gravity brake before in order to enter a stable orbit around ...
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Why were Nix, Cerberos and Styx discovered later than Charon?
Charon, a moon of Pluto, was discovered in 1978. Today we know that Pluto has three additional moons, but they were discovered 3 decades later? Also, Hubble Space Telescope was in operation since 1990 ...
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Titan - Is the source of so much Methane being overlooked?
Is the source of so much Methane on Titan being overlooked?
Tons of very intelligent and knowledgeable people already looked at it, so the answer in undoubtedly "no", so I guess my question is more ...
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Which moon is best? (for gravity assists)
Inspired by my answer to Is a ballistic Jovian capture using the Galilean moons possible from interplanetary entry? in which I discovered that Callisto offers a stronger gravity assist than Ganymede ...
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Many moons in same orbit
Is it possible to have a stable orbit comprised of many moons(>2) that keep themselves roughly equal distance apart?
Sort of like Epimetheus and Janus around Saturn but comprised of many moons.
The ...
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Would a Foucault pendulum work on the Moon and on the Galilean moons?
I wonder whether the Moon and the Jovian moons spin fast enough for a Foucault pendulum to swing on their poles. For instance, I think that it wouldn't swing on Mercury and Venus because these planets ...
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Smallest known asteroid with moon
The asteroid Didymos is only 780m in "diameter" with a moon, Dimorphos only 170m across. Is Didymos the smallest object known to have a natural satellite? Also, contact binaries where the ...
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Why is Enceladus the "most interesting place for astrobiology" in the Solar System other than Earth?
In season 1 episode 1 of Space's Deepest Secrets (IMDB), Dr. Chris McKay, a planetary scientist for NASA, says around 1h:40m into the show, "This is the single most important and interesting place for ...
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Hohmann Transfer Equation of Motion
I'm working on a school project on calculating the Keplerian orbital motion of objects and then plotting/animating the trajectories. One feature I want to include is plotting a Hohmann transfer from ...
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Why couldn't New Horizons try again to search for small moons of Pluto?
I was reading Alan Stern and David Grinspoon's Chasing New Horizons, the story of the quarter-century effort to prepare, enable, and run New Horizons' mission to Pluto. As many readers know, it ...
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Does NASA plan to land on Europa?
I recently studied that life may exist on Europa, an icy moon of Jupiter.
Does NASA plan to land a spacecraft on Europa to study its environment in the near future?
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Is it possible to create an analytical ephemeris from raw position and velocity of a Body?
I would like to have an analytical ephemeris for various bodies of the solar system (planets, natural satellites and asteroid). I have at my disposition spice kernels from which i can extract position ...
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Are there any natural circular orbits?
I just saw How does orbital eccentricity affect positions of Lagrange points $L_4$ and $L_5$? and it questions the difference between circular and elliptical orbits.
We know the Moon does not have a ...
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How close do gravitational 2-body hierarchy levels get?
Due to very few 3-body arrangements being stable (this question thus excluding co-orbital objects like trojans), objects in space usually arrange themselves in a hierarchy of 2-body systems. When the ...
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Which planets and moons can you walk on?
Which planets and moons have a surface where you could survive with a conventional or near-future spacesuit? Assume oxygen, water, and food supplies are accounted for, but roughly current limitations ...
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Where does Io's sulfur come from?
This answer on Movies.SE collects some fascinating facts about the sulfur-dominated surface and atmosphere of Jupiter's moon Io. But it made me wonder where all the sulfur comes from in the first ...
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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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Tallest mountains on the Galilean satellites?
Suppose I want to climb the tallest mountain on each of the four Galilean satellites. Is it known what they are?
Io has one of the most spectacularly tall mountains in the solar system, Boösaule ...
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Has any other term been used for a solar day on a solar system body besides "sol" on Mars?
My interest was piqued by this question and answer. For several reasons NASA needed to refer frequently and extensively to a Martian solar day, and "sol" became the nom du jour. There have been ...
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Keplerian approximations for moons as well as planets
I'm writing code to simulate planetary and lunar orbits in a heliocentric reference plane. I'm using E.M. Standish's Keplerian Elements for Approximate Positions of the Major Planets as my reference ...
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Do Lagrange-like regions temporarily appear around planets with multiple moons?
Lasting Lagrange points only exist where two bodies of mass dominate. But in the midst of for example the synchronous Jovian moons, is there a calendar and map for when a spacecraft can be near enough ...
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How is salt transported from the subsurface ocean and ejected with the plumes of water from Enceladus?
My limited understanding is that the plumes of water vapor and ice seen rising nearly vertically from the ice surfaces of Enceladus and other ice/water covered moons of Jupiter and Saturn are not ...
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Will JUNO do any science of Jupiter's Moons?
It seems like the primary focus of JUNO is to get a better idea of how Jupiter works. The Science Objectives listed on Wikipedia don't seem to include anything about Jupiter's moons, other than a ...
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How were scientists able to experimentally confirm that Saturn's ravioli-shaped moons had highly porous surfaces?
The NASA News article NASA's Cassini Finds Saturn's Rings Coat Tiny Moons says:
The new research, from data gathered by six of Cassini's instruments before its mission ended in 2017, is a clear ...
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Can we detect if Mars has small, stone-size moonlets?
If there is a stone-size moonlet orbiting around Mars, can we detect it?
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Why are most of Jupiter's moons retrograde?
Jupiter's small moons are likely captured objects. I would've expected half of them to be captured in retrograde orbit, between 90 and 180 degrees inclination. But out of 65 lesser satellites, only 11 ...
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Data for Moons in the Solar System with Masses
I'm looking for a simple machine-readable table with basic parameters for all the known moons of the planets in the solar system.
Stumbling around the internet, I can find plenty of sources like this ...
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Is It Easier To Hohmann Transfer to a Retrograde Satellite or to a Prograde Satellite?
Suppose I start on Earth and make a Hohmann transfer to Neptune. After traveling along my initial trajectory, I arrive at the Neptunian system. However, the objects in the Neptune system are going ...
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Is Hydra of Pluto cut unusually, or just darkened on its surface?
The image of Hydra recently released shows a sharply edged black half oval cutting deep into its bottom as in the image below. Is it dark sky behind an open gap we see, or just unreflective matter on ...
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How feasible is a natural satellite (moon) that moves between planets?
I'm designing a world, and I really like the idea of a recurring moon. If a planet were in the proper orbital resonance with another planet, is it possible that moons might occasionally traverse ...
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Could a rogue planet's moons harbor life?
Because stars kill stuff with radiation, flares, etc, then die taking planets with them, might it not be easier for living things to live on a rogue planet's moon? Say you had a rogue Jupiter-like ...
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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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Efficiency of "liquid cooled" RTG
One of the big problems in the vacuum of space is getting heat away. RTG that rely on a temperature differential from the hot to the "cold" side to produce electricity will probably suffer a ...
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Just how locked is Titan? Does it exhibit libration due to eccentricity? Have residual oscillations not yet damped out been detected or ruled out?
Under Where is the Selk crater on Titan with respect to Saturn? there is @BrendanLuke15's comment which provides a helpful hint:
Tidally locked moons have their 0° longitude defined as the 'sub-...
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Iapetus - Destabilized rings to mountains?
I was reading an article about a ring that was destabilized out of orbit on one of Saturns moons. I got there by looking for mountains because of this question (unrelated mostly). Here's a picture of ...
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Delta V required to land and then ascend from the surface of every celestial body
I've been doing some research to figure out how feasible grand tour manned missions to the surface of the moons of each outer planet.
This is related:
Where can I find a delta v map of landing ...
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