Questions tagged [natural-satellites]

Questions on celestial bodies that orbit planets.

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4
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1answer
177 views

What would theoretically be dissolved in the interior oceans of icy moons and planets?

I know we have some indication of "what's in the water" from the plumes of Enceladus, but would other places be the same. For instance, could the deep liquid water of Titan contain dissolved ...
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2answers
307 views

Why does Titan have an atmosphere while similar moons such as the Galilean moons don't?

The Galilean moons of Jupiter are similar in size to Titan and are also protected by their parent planet's magnetic field. How come only Titan is able to maintain an atmosphere?
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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, ...
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2answers
64 views

How massive does a moon have to be to have a stable magnetic field?

Is there a minimum mass or other minimum properties necessary for a body to have a strong, stable dynamo to create a magnetic field conducive for life? For example, would it be possible for Titan to ...
3
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1answer
38 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 ...
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1answer
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Moons within a Gas Giant

Assuming a gas giant is primarily gaseous past our visibility, is it possible that a moon traveling at a sufficient velocity would be able to exist within the atmosphere, or would terminal velocity ...
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4answers
2k views

Could an orphan/rogue planet have a moon?

Is there some reason why an orphan or rogue planet wouldn't have a moon? Let's say it started out in a normal system and then just got flung out by an unstable orbit.
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Slow moving, flashing star-like object in the sky. What could it be?

The sky was particularly clear last night and I noticed an extremely bright star. I thought it was venus possibly but it was too low down and was flickering craziy. That meant that it couldn't be a ...
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2answers
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Do moons experience periods of no sunlight when orbiting “behind” their planet?

I'm writing a story that takes place on the Saturn moon Iapetusand I was thinking that especially since Iapetus only has an inclination of about 17 degrees from the ecliptic, wouldn't there be a point ...
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Which moons do have neutrospheres?

Or in other words: which moons do have ionospheres but not surface-bound ones? The space beneath an ionosphere is called a neutrosphere. I only know of Titan. I know that the Galilean moons and Triton ...
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Ladakh India where the moon (Ramadan moon) is sighted but not in rest of India [duplicate]

Today 22 May 2020 around 3 p.m Ladakh India sighted new moon(Ramadan moon) but not in rest of India.I read many articles acc. To them it is not visible today, then how it was seen from Ladakh... .
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Can we see traces of exo-moon formation?

Our Moon was likely formed by the collision of a Mars-size object with the Earth soon after the planets first formed. Would traces of such an event be detectable by observing the protoplanetary disc ...
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1answer
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How many Kuiper Belt objects have moons? How do we know this?

On 2012 in the New Horizons' The PI's Perspective Alan Stern wrote The Kuiper Belt at 20: Paradigm Changes in Our Knowledge of the Solar System (more also archived) which includes: Most of the known ...
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Are there any moons of minor planets that orbit at high inclination to the plane of rotation of the parent body?

It occurred to me that one of the ringed asteroids or minor planets may answer this question about the alignment of planetary rings. However, it appears that the rings of Chariklo, Haumea and Chiron (...
17
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1answer
632 views

Why do planets and satellites in the Solar system look so wildly different if they came from more or less the same matter?

First, the planets. We have Mercury, which is rocky, no atmosphere. But then we have Venus, which is completely different: thick atmosphere, very hot, geologically active. Then Earth - blue, full of ...
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2answers
742 views

Has any moon achieved “retrograde equatorial orbit”?

There are many moons which have low (almost negligible) inclination and can be considered to rotate at the planet's equatorial plane. For instance, Galilean moons have almost negligible inclination (&...
4
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1answer
140 views

Moons with curlicue paths around our Sun?

I naively believed that since our Moon orbits Earth, and since Earth orbits the Sun, the path our Moon might take around the Sun would be this type of epitrochoid curve: I was surprised and delighted ...
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64 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 ...
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2answers
50 views

What is the naming convention for temporary moons?

Is there a naming convention for temporary moons? Or do they follow the naming conventions of other small bodies? In the case of 2006 RH$_{120}$, 2015 HP$_{116}$, 2020 CD$_3$ and 2020 SO, the first ...
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1answer
49 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 ...
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1answer
68 views

Why does an irregular moon point its longest axis towards its parent planet?

I'm reading the book Ice Worlds of the Solar System. Page 62, it states that an irregular moon should point its longest axis towards its planet. Why is this the more stable configuration?
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1answer
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Why are the moons of Neptune sorted by diameter?

The five moons closest to Neptune are sorted by increasing size. Naiad < Thalassa < Despina < Galatea < Larissa. The trend continues with Proteus and Triton, only interrupted by Hippocamp, ...
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3answers
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Are moons geologically active?

Are there natural satellites in the Solar System that are geologically active? This includes volcanism, existence and motion of tectonic plates, et cetera. Is it a common or a rather rare feature ...
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1answer
302 views

What caused these strange craters on Hyperion?

I was looking at pictures of the moons of Saturn and noticed that the craters on Hyperion have a strange shape, somewhat resembling sinkholes. They look a lot deeper than the impact craters on other ...
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2answers
111 views

How to calculate the frequency of a gas giant eclipsing the sun from a moon?

Say you have a moon around a gas giant which goes around a star. If the moon has an inclination of around 0° relative to the gas giant's orbit, the gas giant will eclipse the star every orbit of the ...
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2answers
75 views

What would a moon with a six-month orbital period look like from the earth?

This is a kind of follow-up question to "What orbital period would produce one New Moon (and one Full Moon) each year?" Given the six-month orbital period that is needed to produce one New ...
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1answer
61 views

Does tidal locking also slowly reduce the orbiting body's axial angle?

The Moon is tidally locked to the Earth, and it has an axial angle of 6.687 degrees relative to its orbital plane. I'd like to know: did the Moon start out with a higher axial angle? In other words, ...
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3answers
4k views

Do celestial objects need to be big to have liquid water on their surfaces?

I mean no asteroid, planetoid that I am aware of has water on its surface. It is way more common to see ice in it. So I figured that the size of the celestial body has something to do with the cycle ...
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1answer
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Is there a name for a planet and its moons/satellites?

I'm wondering if there's a name that encapsulates the concept of a planet and the objects that orbit in its gravity. There's a solar system that encapsulates a star and its multiple planets and other ...
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115 views

Is a literal instance of Russell's teapot possible?

Much has been said about Russell's teapot, and I accept as obvious that a teapot would be too small to be detectable in an orbit around the Sun by any reasonable method today, or by any method that ...
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2answers
121 views

How to find the mass of a planet not knowing the gravitational constant?

So I found this problem, I know the gravity of earth $g_0$, I found the orbital speed of one satellite using this equation $\frac{GM_em_s}{(R_e+h)^2}=m_sa$ ($M_e$ is the mass of earth, $m_s$ is the ...
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2answers
151 views

When would we detect a tiny meter size natural satellite in a geostationary orbits?

A natural, tiny (meters-size, maybe 10.000kg mass) natural satellite could be trapped in a geostationary orbit. I wondered for quite some time: When and how are we able to detect these satellites? I ...
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1answer
50 views

Angular diameter result confirmation

Not being a math-minded person at all, however basic it might appear to be to all of you in this particular question, I would like to get the following calculation confirmed. I'm trying to calculate ...
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1answer
50 views

How did the orbits of Phobos and Deimos circularize?

The satellites of Mars might be captured asteroids. But Phobos has an eccentricity of $0.015$, and Deimos of $3\times10^{-4}$. If they were captured, they likely were captured with rather eccentric ...
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3answers
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Why don't the inner moons of Jupiter have tidally-induced volcanism?

Volcanism on Io is caused by the fact that it is tidally heated. There are four moons that are closer to Jupiter than Io with higher eccentricities, yet they don't seem to have any volcanism at their ...
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2answers
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How many satellites orbit their planet faster than the planet rotates?

Phobos is so close to Mars that it orbits Mars much faster than Mars rotates. This means that it rises in the west and sets in the east, even though its orbit is prograde. Are there any other known ...
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0answers
35 views

How many moons do we know are shepherds?

Shepherd moons are natural satellites near the edge of a planetary ring that have an influence on the shape and size of the ring due to their gravity. So it is possible for a satellite to be near the ...
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2answers
398 views

What is the minimum mass of a celestial object so that it can have a moon?

I was wondering how massive something have to be so that it it can attract moons by pop culture standards (ellipsoid/round shape). Could a planetoid have a moon? What is the relation between the mass ...
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Why was the diaeresis removed from Pasiphae?

The Gazetteer of Planetary Nomenclature notes that the spelling of Jupiter's moon Pasiphae was changed from Pasiphaë in July 2009, i.e. they removed the diaeresis. I've been unable to track down the ...
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1answer
81 views

If a planet gained too many moons could the tidal forces of those moons rip the planet apart?

Or would the planet just be subject to extremely intense tidal forces instead?
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Keplerian Elements for the Moon and Earth around their Barycenter

So I'm looking to replicate the inner Solar System to a decent degree of accuracy. So far I've been utilizing the Keplerian Elements and Equations for the planets, as shown here. There is one issue ...
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Why doesn't the moon always follow the same path? Or why aren't the moon's apoapsis and periapsis fixed?

I have seen many times that the moon doesn't follow the same path. Sometimes the moon gets very close to earth which is shown in the news. If the periapsis of the moon is soo close then why doesn't a ...
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1answer
192 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 ...
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1answer
153 views

Why isn't there a large gap in the number of captured moons Jupiter and Saturn have?

Given that Jupiter is roughly 3x as massive compared to Saturn and is located right next to the asteroid belt, it feels that Jupiter should easily have a larger amount of captured moons. However ...
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2answers
614 views

Up to 384 minor planets (including Pluto) qualify as planets?

In 2006, the International Astronomical Union redefined the definition of planet in order to exclude Pluto, Eris, and several other objects whose category was disputed. This new definition of a planet ...
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8answers
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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: ...
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1answer
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Is a Procyon - brown dwarf - Jupiter - superearth - Mars - Pluto system theoretically possible? [closed]

I once conducted a thought experiment and with some amateurish calculations based around Hill sphere and Roche limit came up with semi-major axis distances like this: ...
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3answers
3k views

Do moons have moons?

Have we discovered any natural satellites of natural satellites of planets or dwarf planets? Even very small, or relatively short-lived - e.g. ringlets around Saturn's moons, some meteorites orbiting ...
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Help identifying a very slow-moving object during meteor shower photography

I just wonder if anyone could shed any light on this puzzle. Two nights ago whilst I was out photographing the Lyrids meteor shower from the UK something else showed up on my images when I checked ...
8
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1answer
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When was it realised that most major moons orbit in the equatorial plane of their parent planets?

Inspired by the discussion of the moons of Uranus providing a clue to the planet's axis of rotation in this question, I'm wondering when it was realised that the major satellites are typically located ...