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Questions tagged [natural-satellites]

Questions on celestial bodies that orbit planets.

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10 votes
2 answers
2k views

Can individual rings of Saturn be considered satellites?

By this definition, is every small rock orbiting Saturn considered a natural satellites? What is the widely accepted terminology for moons? The Wikipedia article is ambiguous on this. So, what terms ...
2 votes
2 answers
121 views

What exactly was "The curse of Sisyphus" and why did it take so long to find out about the radar detection of its companion?

This answer to First satellite of an asteroid (or double asteroid) ever imaged by delay-Doppler radar? mentions that Wikipedia's 1866 Sisyphus; Binary system says: In 1985, this object was detected ...
4 votes
0 answers
99 views

What are the odds of a planet with an eclipse every time the moon rotated around the planet?

If the orbital plane of a planet and its moon were sufficiently aligned, the moon could cause a solar eclipse every lunar month. What are the odds of that happening? To answer, I would guess that one ...
5 votes
1 answer
267 views

Will Lunar Months be the same length Millions of Years in the Future?

If I remember correctly, the amount of time it takes for the moon to rotate around Earth is getting longer over time. Is this true, and if so or the opposite is true and a lunar month is getting ...
4 votes
2 answers
208 views

Are there areas within Jupiter's magnetosphere without powerful radiation?

I know Jupiter has powerful radiation belts, but I'm wondering if there are places within the magnetosphere that are relatively calm. I'm asking about Jupiter (a gas giant we know) because I'm curious ...
18 votes
6 answers
13k views

Moon's orbit around the Sun

The Earth revolves around the Sun and the Moon revolves around the Earth. Out of curiosity I started thinking about the orbit of the Moon around the Sun and expected (assumed) it to be as follows: ...
3 votes
0 answers
124 views

Two Suns vs Two moons in the Sky

How rare is it to have 2 stars or 2 celestial bodies at least as big as our moon and sun in the sky of a habitable planet? What are the chances of both?
5 votes
2 answers
2k views

Sum of the Masses of All Moons in the Solar System

I'm looking for the total mass of the moons in the solar system in Earth Mass this would be include the 67's moons of jupiter, the 62's of saturn, the 27's Uranus and the 14's for Neptune. it's a ...
2 votes
0 answers
88 views

Simple position calculation of solar system satellites

I'm looking for a simple way to calculate positions of satellites in the ecliptic of the date. I've found an implementation for Jupiters satellites in the Astronomical Algorithms by Jean Meeus, and I'...
5 votes
3 answers
200 views

Why are there gaps in the size distribution of solar system moons?

Looking at the moons natural satellites in the solar system, the larger ones appear to fall in a few groups of sizes. Eyeballing the above picture, there appear to be a bunch of big moons (the ...
1 vote
1 answer
80 views

Natural satellites sorted by albedo

Can I find a list of natural satellites of the Solar System with the average albedo for each one ? Enceladus, for instance has an albedo of 0.81 and Triton has an albedo of 0.76. But has someone ...
26 votes
6 answers
6k views

Definition of a moon in an exam: "A satellite of a planet that *doesn't produce light itself but reflects it*" - is there relevance for the emphasis?

In a 5th-grade exam (for 10-11-year-old pupils in Finland), there was a question, "What is a moon?" The model answer was: "A satellite of a planet that doesn't produce light itself but ...
3 votes
1 answer
262 views

Are there any estimates of the Roche Limit for 152830 Dinkinesh?

The Lucy spacecraft recently flew past the asteroid 152830 Dinkinesh on its way through the asteroid belt and photos show that Dinkinesh has a moon consisting of a contact binary. (Image is Public ...
12 votes
3 answers
5k views

If the Earth had another moon would it be better protected from asteroids?

Would the moons get struck by asteroids instead of the Earth or would the moons attract more asteroids and make it more likely the planet gets hit?
1 vote
0 answers
92 views

Why Saturn has more Moons than Jupiter? [duplicate]

Why does Saturn have more moons than Jupiter, I know the grand tack hypothesis suggests Jupiter migrated from 3.5 au to present orbit but given that Jupitern is more massive meaning a larger ...
4 votes
2 answers
360 views

What celestial body (inside the solar system) has the highest flattening ratio?

As a planet, Saturn has the highest flattening(ellipticity) which is 0.09796. So, it makes Saturn with the largest equatorial bulge as a planet and as such Saturn is the flattest planet. However, I ...
1 vote
1 answer
213 views

Determining the position of the North Node using math?

I have to be honest. Been learning python for few months but when I saw this code I was blown away, mainly by its simplicity and secondly by not understanding it .. can someone help me understand ...
0 votes
1 answer
428 views

What would happen to the Galilean moons and Titan if Jupiter and Saturn disappeared?

The Moon reportedly doesn't "need" the Earth to revolve around the Sun. If the Earth wasn't there, the Moon would continue its current path from a heliocentric reference frame around the Sun. My ...
1 vote
0 answers
53 views

Question regarding potential moon sizes

I am planning out ideas for a science-fiction world, and I want to make sure that what I include is reasonable and mathematically sound (outside of things like FTL as that is neccessary for the story ...
3 votes
2 answers
112 views

Could a super Jovian planet have mild radiation belts?

Will a large gas giant always have powerful radiation belts or could a milder radiation environment exist even around super Jovian planets? I know Jupiter’s radiation belts are so strong due to a ...
7 votes
2 answers
791 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 ...
5 votes
1 answer
194 views

Are there any bodies in the solar system whose rotation is almost tidally locked or barely tidally locked?

The Moon's rotation is firmly tidally locked to the Earth and the Earth's rotation is firmly tidally unlocked with respect to the Moon. I gather that Mercury's rotation is tidally locked in a 3:2 ...
2 votes
1 answer
74 views

What secondary and tertiary conclusions can be drawn from the temperature characteristics of lunar soil sent by ISRO Chandrayaan 3?

ISRO Chandrayaan 3 released the following data today about the temperature characteristics of lunar soil. What secondary and tertiary conclusions can be drawn it? More specifically, what may be the ...
0 votes
0 answers
49 views

Is there a minimum size for a moon? [duplicate]

Is there a minimum size for a moon? Is there a lower bound below which it's simply considered as being a rock? Or could you can every piece of rock and Ice in Saturns rings as an individual moon.
3 votes
2 answers
331 views

Is there a way to estimate or calculate the tidal range induced on a water-bearing planet?

Consider a system in which a central star is orbited by a planet with liquid water oceans, which is itself orbited by a moon. Given the masses and distances between these three objects, is there some ...
3 votes
3 answers
243 views

Will all satellites get inevitably tidally locked to their planet?

Are there cases or conditions in which an object orbiting another one (e.g. a satellite and its planet) does not get tidally locked to it? For example, in this question, it is mentioned that a large ...
4 votes
1 answer
153 views

What moons have cleared their orbits?

The Wikipedia article Clearing the Neighborhood lists three numeric parameters that can be calculated for bodies orbiting the Sun as a way to indicate orbital dominance: Stern and Levinson's $\Lambda$,...
2 votes
1 answer
152 views

Could there be bacteria in the 6000 km water jet of Saturn's moon discovered by the James Webb telescope?

James Webb telescope discovers gargantuan geyser on Saturn's moon, blasting water hundreds of miles into space. If there is life inside the moon Enceladus perhaps now it is airborne. Could water carry ...
19 votes
3 answers
6k views

Is it possible to have satellites (natural or not) orbit the same celestial object in different directions ? (clockwise, counterclockwise)

Is it possible to have satellites (natural or not) orbit the same celestial object in different directions, or is the orbital direction dependent on the celestial object's spin? Also, is the direction ...
3 votes
1 answer
1k 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 ...
0 votes
1 answer
99 views

In Jovian and Saturnian moons with subsurface oceans, why doesn't the surface sink?

The surface of some of the Jovian and Saturnian moons for which subsurface oceans have been proposed contains materials denser than water like rock. What keeps the surface from sinking under the ...
2 votes
2 answers
2k views

What kind of effects would two moons have on an earthlike planet?

On Earth our moon has several effects: it generates two high and two low tides a day; it slows down the spin of the planet and stabilizes its wobble, etc. So, what possible effects could two moons, ...
2 votes
1 answer
73 views

How close does a double-planet have to be to provide magnetic protection to a smaller body?

A spinoff of my previous question, regarding the Orbital Stability of a Double Planet System. Imagine two closely-orbiting bodies with a semi-major axis of 79,250 km. One of which is 2M🜨, with a ...
3 votes
1 answer
198 views

Orbital Stability of a Double Planet System

I recently found an article claiming a double planet system needs to be at least .5 AU from its parent star to be stable for billions of years. It was specifically talking about two same-mass bodies, ...
5 votes
1 answer
140 views

What are these bumps on Europa?

The surface of Europa is famous for all the criss-cross lines thought to be cracks in the ice above a water ocean that somehow re-freeze. But in the photo below I also see a lot of raised "bumps&...
-5 votes
1 answer
1k views

I think I saw a satellite disappear?

I was gazing out of my balcony, and all of a sudden I saw this red light move across the sky. I thought was that it was a star at first, but it didn't blink, so I thought maybe it was a planet but it ...
7 votes
2 answers
489 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 ...
1 vote
0 answers
135 views

What is the brightness and size of Jupiter from the Galilean moons, the closest moon, and the farthest moon?

From the Moon, Earth would appear 4 times larger than the Moon seen from Earth, and the magnitude of a "full earth" is around -17. However, Jupiter from the Galilean moons appear much larger ...
9 votes
2 answers
3k views

How would ocean tides work on a tidally-locked planet?

Since the tidal bulge is always in the same place, how would that affect ocean tides? Would they change throughout an elliptical orbit, due to changing distance from the star? How exactly would they ...
5 votes
2 answers
319 views

How would a small TCO (temporarily captured orbiter) or other natural Earth satellite most likely be detected?

A sentence from the abstract of The population of natural Earth satellites states: At any given time there should be at least one NES of 1-meter diameter orbiting the Earth. The average temporarily-...
2 votes
0 answers
77 views

If Ganymede had a thick, Earth-like atmosphere, would the surface be protected from Jupiter's intense radiation?

Obviously, this is a totally hypothetical, alternate version of Ganymede, since it would also need to have more mass and a stronger intrinsic magnetic field to hold onto a substantial atmosphere. But ...
34 votes
1 answer
6k views

Why do Jupiter’s moons have so much water?

Why do Jupiter’s moons have so much water by mass? Did all the bodies in the solar system start out with this much water and the planets closer to the Sun simply lost it to space?
6 votes
1 answer
64 views

Does a more massive main proto-body result in more massive satellites? More satellites?

Suppose that we have a forming protostar and an accompanying protoplanetary disk. Does the mass of the protostar have any direct relation to the masses of resulting planets or amount of resulting ...
2 votes
2 answers
343 views

What would be 1 hour equivalent on these moons of Jupiter and Saturn compared to earth? And their astrobiological implications

Considering the distance from and velocity of Sun, Saturn, Jupiter, thermal energy due to motion other than that adding/combining to velocity, and the individual mass and velocity of the particular ...
2 votes
0 answers
77 views

Besides Luna, are there any models of how moons become spherical and round?

Question Given the theorized exceptional formation of Luna, (Giant-impact Hyphothesis, Wikipedia), are there any similar animated models of how the other, much smaller, moons in our solar system ...
4 votes
1 answer
277 views

If you were standing on a habitable moon of a gas giant, what would the planet look like during the day vs the night? [closed]

If you were standing on the proplanetary side of a habitable moon of a gas giant, and the moon had a thick enough atmosphere to make the sky blue, how would the gas giant look during the day? Would it ...
4 votes
1 answer
123 views

Is the process responsible for Triton's nearly perfect circular orbit going to happen in my fictional world?

First of all, I'd like to point out that I'm a worldbuilder and I like my worlds to be as physically possible as... possible. I am in the process of building a world with a habitable moon orbiting ...
4 votes
3 answers
157 views

Orbital terminology for satellites relative to one another

Basic question, but I'm trying to describe a planetary system and coming up short on vocabulary. Do either of the following exist?: A word for the closest pass between two satellites orbiting the ...
12 votes
2 answers
1k views

What is the longest natural bound orbit chain observed?

Define a bound orbit chain as a list of successively less massive bodies, each in a bound orbit with the bodies preceding it in the list. Then an example of a bound orbit chain would be: <Sun, ...
8 votes
2 answers
3k views

The moon rises at a different time each day, but that difference changes. Why?

Let's say the moon rose at 5pm yesterday and 5:30pm today. The difference is 30 minutes – but that difference changes from day to day and can be anywhere between twenty-some to seventy-some minutes. ...

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