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Questions tagged [natural-satellites]

Questions on celestial bodies that orbit planets.

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2answers
4k views

Is there any known moon of a moon? [duplicate]

As far as I understand, a moon is an object in permanent orbit around a planet, dwarf-planet, asteroid, etc. If there was another object permanently orbiting this moon, would that be a moon-moon? Is ...
2
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1answer
60 views

How was Cruithne's orbital time calculated?

How was it determined that Cruithne takes 770 years to complete its cycle with Earth? Janus and Epimetheus were disovered long enough ago, and have short enough cycle times, that we've had time to ...
9
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1answer
2k views

Which Saturn satellite passes closest to Saturn's rings and at what distance?

I was using Stellarium to watch Saturn from its moon Pan and I saw the rings were very close to this moon. Now Saturn's rings extend for a large distance so several moons see them from close. I was ...
5
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2answers
100 views

What variables are needed to calculate simple horseshoe orbit times?

EDIT This was NOT a duplicate of Horseshoe orbit cycle times. But that other question has been deleted, regardless. My original question asked for the answer to the equation(s), and provides many of ...
6
votes
1answer
171 views

Why is Uranus able to support a regular satellite system?

Uranus has an obliquity of 98° which means that the mutual inclination between a satellite orbiting in its equatorial plane and the orbit of Uranus around the Sun would exceed the critical angle for ...
6
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2answers
78 views

How long is a “lunar month” in Jupiter?

For Earth, the lunar month is well known. But Earth has only one moon. But on Jupiter, how long does it takes for the same moon configuration to appear in the "sky" of the planet? For the sake of ...
3
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1answer
54 views

How do they measure sub-centimeter wave height on a moon of Saturn?

Michael Stevens from V-Sauce has a video called The Mandelbrot Set on a different channel. At 12:56 he says: There’s a moon of Saturn that has liquid hydrocarbon ...
0
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1answer
82 views

Can a moon have a moon? [duplicate]

Is it possible for a natural moon to have a natural moon? What is the limit to when satellites on satellites becomes to unnatural for it to be possible?
2
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0answers
63 views

Moons of migrated giant planets: Icy, Rocky, or none at all?

My understanding is that gas and ice giants form outside the "snow line" of their protoplanetary disk, then sometimes through gravitational interactions they are able to migrate into the inner star ...
8
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2answers
137 views

Natural satellites for Mercury

Would it be possible that Mercury had a natural satellite but the gravitational pull from the Sun became so overwhelming from it growing over the years that it just sucked in Mercury's moon?
3
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1answer
285 views

How many moons in the solar system have water?

I've heard of a few moons in the solar system that have water, like europa and enceladus. However, I can't find information about whether there are other moons as well. I'm guessing there are more, ...
2
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1answer
113 views

Is there enough light to grow plants in the ocean of Europa?

What is the underwater temperature of Europa? I know Jupiter emits infrared light but does it emit any light able to support plant life of any type on near by Moons? Can under water volcanic activity ...
9
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0answers
99 views

Why haven't more captured small moons been found?

Shouldn't captured moons have the same size distribution as asteroids? And asteroids are more common the smaller size they are. Moons are likely captured if they are in highly inclined orbits, and ...
3
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2answers
120 views

What is the minimum size to be a natural satellite?

Would a smaller satellite be more stable around a smaller planet where the same satellite would not be stable or last around a larger planet? I added the picture to show how moon size planets can ...
4
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2answers
92 views

Could a moon be passed from one planet's orbit to another?

Like if you had two planets that had a close orbital path could the moon be pulled away from the first planet?
5
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1answer
42 views

How far from the Sun can an Earth TCO (temporarily captured orbiter) go after leaving?

Objects which are temporarily captured into an Earth-Moon system orbit (temporarily captured orbiters or TCOs) by definition will leave this orbit. While the term suggest an Earth orbit, it's really ...
2
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1answer
66 views

Why are gravitational perturbations stronger at larger semi-major axes?

Why are mechanisms such as the Kozai-Lidov effect more prominent at at large semi-major axes? If we had a binary system of a primary and secondary body, with the third perturber as the Sun. Why is it ...
4
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2answers
191 views

What is minimal aperture/magnification to recognize phases of Galilean moons?

Given you take a (non-amateur) refractor telescope, what are aperture and magnification required to recognize phases of the four Galilean moons? What did Galileo see: http://www.astro.umontreal.ca/~...
3
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2answers
118 views

Is it possible for a planet to have multiple moons in a nearly stationary orbit?

I have done a lot of searching online and while I have been able to find out that theoretically a moon could exist in a near-synchronous/stationary orbit, I am wondering if it is possible for multiple ...
14
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3answers
2k views

Would an analogue of the definition for planets also work for moons?

This is a follow up question to What exactly is a "moon"? The conclusions I draw from James K's answer is that the IAU should define what a moon is. They haven't done so yet, but they should. The ...
6
votes
3answers
280 views

What exactly is a “moon”?

Recently some new moons of Jupiter were discovered. However the moons are pretty damn small indeed - only a few kilometers wide. That makes me wonder if they should even be called moons in the first ...
1
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1answer
143 views

How did “oddball” Valetudo, Jupiter's new prograde moon, end up in a wider orbit?

I just saw this question and that got me to this NASA page which led me to this scientific article. “Our other discovery is a real oddball and has an orbit like no other known Jovian moon,” ...
18
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1answer
3k views

Did we discover 10 or 12 new moons of Jupiter?

I saw multiple news sites reporting that a team discovered 12 new Jupiter's moons: c|net - Twelve new Jupiter moons found, including one reckless one Discover - Jupiter’s Got Twelve New Moons — One ...
2
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1answer
98 views

Changes of the velocity of the Moon due to impacts from other objects?

Has the moon’s velocity changed since ‘shortly’ after it’s formation due to impacts? Wouldn't it be likely that a significant collision would have occurred over such a long period of time? It ...
3
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1answer
71 views

Number of planets in a habitable zone with large moons [closed]

Excluding gas giants, roughly what percentage of planets in the habitable zones of their stars would have large moons like Earth does, as opposed to Mars and its small moons/captured asteroids?
5
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2answers
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Say we were to bring Titan to Earth's orbit. How much would its atmospheric pressure change?

I've heard one of the reason why Titan has such a thick atmosphere is because of its really low temperature. So say that were were to magically bring Titan to the Same orbit as Earth, and the moon ...
1
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2answers
87 views

Can a planet's gravity rip out its moon's atmosphere?

We all know that solar flares can rip a planet's atmosphere if the magnetic field is weak.Solar flares travel at tremendous speed so when they hit the gas molecules of a atmosphere the molecules are ...
3
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1answer
103 views

Is there a significant temperature difference on the moon from apogee to perigee or vice-versa?

Do those few thousand kilometers of difference going around the earth significantly affect the amount of thermal energy the moon receives from the sun to warm up its surface? Also, are there more ...
5
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1answer
97 views

How can a rotation period of a planet's satellite/moon be “chaotic” (like Hyperion around Saturn)?

According to wikipedia (see info below image) Hyperion's rotation period around Saturn is "chaotic". What does that mean? The period (in days/hours) is different every rotation without any law ...
1
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1answer
56 views

New NEOs are found daily. Is there any evidence gravity is pulling them to a centralised location?

With all of the new NEOs (near-earth objects) are they being pulled in or are they interacting with each other?
2
votes
1answer
76 views

How old are Janus and Epimetheus?

How old are Janus and Epimetheus, and are they believed to have formed out of a collision? (I think would explain their shared orbit). Not the age of their elements, which should be similar to the ...
6
votes
2answers
103 views

horseshoe orbits

I'm designing a moon system for a fictional setting, and recently came across the idea of horseshoe orbits. The gist of my question is how many objects can share a horseshoe orbital at a time? I ...
2
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1answer
64 views

Do the number of moons a planet has affect the speed of the planet's rotation?

Would the tidal forces of multiple moons interacting upon a planet speed up or slow down the day length of the planet? I was thinking that maybe the planet's day length would be slowed down due to all ...
1
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0answers
103 views

How do I calculate the hour angle of a planet's moon from a point on that planet's surface?

I'm worldbuilding and I'm trying to construct a standing stone calendar that'll accurately denote where to look for my planet's moon at its four major phases from 53.8 degrees South. So, I need the h0,...
9
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1answer
378 views

How can tidal heating lower Io's orbit?

This answer to the question Is Io a magic energy machine? suggests that the energy from the internal heating of Io due to tidal "squishing" as it moves cyclically closer and farther from Jupiter in ...
2
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2answers
287 views

Which moon has a scar as if it was torn in half and put back together?

When I was a kid I had several beautiful encyclopedias. In one of them there was a description of moon orbiting on of the gas giants that had huge ripples all along its surface. It said in the text ...
2
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1answer
60 views

Is it possible for a moon to only be out at night?

(For the sake of this question, let's assume that all other factors are malleable.) Essentially creating a permanent lunar eclipse, could a moon orbit around a planet so slowly that it is always ...
8
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2answers
255 views

Eventual outcome of tidal acceleration and deceleration

So, I know the Moon experiences tidal acceleration from the Earth. And, from what I've read, if not for the fact that the sun would boil away the oceans and engulf both of them first, about 50 billion ...
3
votes
1answer
73 views

What is the official term for a relationship between a planet and its moons?

Sorry if this is a dumb question, I could not find anything naming this in my astronomy books, and Google searches only seemed to show me pages about astrology, [sarc] because naturally, human ...
4
votes
2answers
95 views

When will the next series of mutual eclipses of Jupiter's moons begin?

When I was young (I won't tell you when) I saw one of the four Galilean moons of Jupiter suddenly disappear while watching through a small refractor. It wasn't a coincidence, I'd seen the prediction ...
2
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2answers
154 views

Is it possible that a satellite creates a forever eclipse? [closed]

So, to add a bit of context, I’m doing the NaNoWriMo challenge, which consists of writing a novel of 50k words in one month. My whole idea is based around the following question: What would happen if ...
2
votes
1answer
95 views

Could a binary system of two planets with oceans reflect each other?

If there were two earth-like planets in a binary system and one of them had landmasses, and the other one had oceans covering a significant amount of its surface, could you see the continents of the ...
9
votes
1answer
615 views

Why is Enceladus the only geologically active moon among its neighbours?

My understanding of why Enceladus is geologically active is that tidal forces from Saturn and - to a lesser extent - from the nearby larger moon Dione provide heat to the moon's interior, just like ...
2
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2answers
280 views

Could a moon orbit two planets at once?

Let's say you had a binary planet system of two earth-sized worlds with about the same mass. Could a stable moon orbit around the barycenter of both planets? If so, is there a limit to the mass of ...
1
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1answer
157 views

Could binary gas giants have ring and moon systems?

Would any moons/rings around either of the gas giants stay intact or get ripped apart by the tidal forces between the two giants? If any moons/rings are able to form around either of the giants, is ...
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0answers
39 views

If the moon's orbit decays- how would it effect the moon's phases? [closed]

If a planet passed near the moon and caused its orbit to decay down to earth- how long could it take and how would that effect the visible phases of the moon on earth?
2
votes
1answer
160 views

Io: Why so much sulfur?

Io is the only body in the Solar System whose crust is dominated by sulfur and its compounds. Carbon and nitrogen are also very common in the universe but we don't see them or their compounds in Io's ...
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1answer
79 views

Is there a timekeeping word for the orbit of a moon?

For a planet, we can colloquially refer to its period of rotation as a "day" and its period of revolution around its parent star as a "year." Some worlds have unique terms, such as Martian days being ...
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3answers
80 views

What of the following moon-situations would be better?

Okay, so imagine that there is an Earth-like planet, with the following conditions: It's further from it's sun than the Earth is from the Sun (not much, but enough for weather to be a little colder ...
1
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1answer
118 views

If I had a horseshoe orbit of two moons…

Consider an Earth-like planet, with two moons. I guess the two moons would have to be smaller than our own, for the system to be stable. Is that stable? I did some research, and apparently Janus and ...