Questions tagged [planet]

Questions on astronomical objects orbiting a star massive enough to be rounded, not massive enough to cause fusion, and which have cleared its orbit of planetesimals.

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Why are triple conjunctions in a resonance forbidden?

I was reading the Wikipedia article about orbital resonance and noticed that Laplace resonances forbid triple conjunctions. This seems to be supported by the Io-Europa-Ganymede system and the Nyx-Styx-...
WarpPrime's user avatar
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1 vote
2 answers
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Star and Planet temperature relationship

Let's assume there is this planet with no atmosphere, no geothermal activity and an average temperature $\ T_p$. Now, if the distance between the planet and the star is $\ d$ and the radius of the ...
Lorenzo Boole's user avatar
9 votes
3 answers
2k views

How does NASA figure out orbital period and mass data for planets and other celestial bodies?

Does NASA calculate orbital periods using Kepler's Laws, or do they measure and observe it in some way? If the latter, how do they do so? Similarly, does NASA calculate the mass of bodies using Kepler'...
user44607's user avatar
  • 101
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1 answer
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Why is there a deviation between the ratio of $a^3$ and $T^2$ for the outer planets?

The Wikipedia article about Kepler's third law includes a nice table about the ratio between $a^3$ and $T^2$. However, for Mars, Jupiter, Saturn, Uranus, and Neptune, the ratio $\frac{a^3}{T^2}$ in $...
WarpPrime's user avatar
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4 votes
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New to Astrophotography

I just had a quick question on my telescope I recently purchased. I have a Canon Rebel XTi and I paired that with the William Optics Guide Star 61 Guidescope. The Specs on the Scope are: Guide Scope ...
chris fox's user avatar
4 votes
2 answers
185 views

Is the satellite of a small star in a binary solar system a moon or a planet?

What exaclty distinguishes a moon from a planet? In a binary solar system that has a large star in the center and a smaller star - among some planets - orbiting that large star, and the smaller star ...
matthias_buehlmann's user avatar
0 votes
1 answer
111 views

Why do planets' orbital velocities drop off by less than a third when twice as distant from the sun, rather than three-quarters? If gravity is $1/4$?

Looking at the speeds of the planets in our solar system when traveling around the sun and their distances from it (or, using Kepler's third law,), it seems that when a planets distance is doubled, it'...
Kurt Hikes's user avatar
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1 answer
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Could there be planets that are not rotating around their axis yet are in orbit around a star?

The title really says it all. I know that there are planets like Earth that rotate around their axis and also around their star. I know that there are tidally locked planets which always have the same ...
Vilx-'s user avatar
  • 413
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1 answer
568 views

How does one find out how often planets align?

I am trying to figure out how often Neptune and Uranus align. Internet sources says that Neptune's orbit around the sun is 165 years, and that Uranus' is 84 years. It also claims that the two planets ...
Constantthin's user avatar
1 vote
0 answers
33 views

List of J₂ values for solar system bodies beyond the planets; are there any prolates?

J₂ values for the planets can be found in several sources including each planet's planetary fact sheet. Without looking I'm going to assume they are all positive (oblate) because each planet rotates ...
uhoh's user avatar
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Which planet, viewed from which other planet would appear the largest?

Inspired by this question, I'm curious: Which planet in our solar system, when viewed from which other planet, would appear the largest/brightest? You probably can't really see much of Uranus from ...
Darrel Hoffman's user avatar
0 votes
1 answer
65 views

Sun expansion's effect on planets

When the Sun gets to the age at which it will rapidly expand what effect would it have to the outer planets and it's moons? Would it make new habitable areas of the solar system?
Michael's user avatar
13 votes
4 answers
3k views

Could Neptune be viewed with the naked eye from Uranus?

Which star or planet in our night sky can match what Neptune would look like when viewed from Uranus, or one of its moons? The answer would be for the most favourable condition, which is when Neptune ...
Constantthin's user avatar
4 votes
1 answer
162 views

Is it possible to have a positive rational number of months (more than 1) in a year?

It is possible for a planet to have orbital resonance with a sun (e.g. Mercury has a 3:2 spin resonance with the sun). It is also possible for a moon to have orbital resonance with a planet (e.g. our ...
Daniel-耶稣活着's user avatar
7 votes
1 answer
900 views

What are the "weather" (and other) implications of long "days" and short "years" on Mercury?

On earth, it takes a "day" for it to rotate on its axis, and 365 of these days for it to revolve around the sun. On Mercury a "day" that encompasses a rotation represents 59 earth ...
Tom Au's user avatar
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2 answers
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Given a location and a time on another planet, how do you determine how many hours before or after sunrise is it there?

I'm actually not so much interested in sunrise/sunset times. What I want to know is how to relate local planetary coordinates (e.g., planetary lat/lon) to, for example, heliocentric coordinates at a ...
bob's user avatar
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1 vote
1 answer
109 views

Effects of a supernova shockwave or gravitational wave to a nearby planet's orbit?

I've been reading about recent reports regarding COCONUTS-2B, a planet with the longest orbital period known - 1.1 million years. As a previous question asked, What precisely leads to planets like ...
WarpPrime's user avatar
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6 votes
1 answer
129 views

How could a captured asteroid enter a circularized orbit?

Ok, the simple answer would be through gravity assists from moons, taking a ballistic capture orbit into a circular orbit. I am wondering the chances of a ballistic orbit becoming a stable (on the ...
WarpPrime's user avatar
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3 votes
2 answers
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Is it possible for a planet to heat up its moon to habitable temperatures solely through infrared radiation?

Stars are powered by nuclear fusion and the energy released radiates through their surface as heat. But all objects radiate away some form of electromagnetic radiation depending on their temperature. ...
user177107's user avatar
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Frequency of planet masses in any given star system?

This question is a follow-up to the expected distribution of planet masses in a given system. I am wondering, what is the distribution of various planet masses in any given system? I am expecting a ...
WarpPrime's user avatar
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3 votes
1 answer
125 views

Why is planet visible very good in a specific time of the year?

I'm trying to solve this task: Why do periods of good evening visibility of the planets usually come in winter and spring, and morning ones - in summer and autumn? Could somebody please explain what ...
ALiCe P.'s user avatar
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9 votes
1 answer
212 views

What's the expected distribution of planet masses in a given system?

Given that the mass of a planet at a given orbital distance r is dependent on the protoplanetary material in the neighborhood of r at the time of formation (assuming no planetary migration), what ...
Anthony Khodanian's user avatar
1 vote
1 answer
84 views

Is life possible on other celestial objects (apart from planets) even theoretically? [closed]

For example, asteroids, comets, stars, heliosphere etc?
Abhay's user avatar
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3 votes
1 answer
129 views

Where can I find planetary rotational axis direction?

I can find axial tilt of planets easily, but that doesn't specify the direction of that tilt, i.e. planet's rotation axis may be anywhere in circle defined on a sphere by axial tilt value. And I can't ...
Aberro's user avatar
  • 133
3 votes
1 answer
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Not getting quality images in telescope

I have a Newtonian telescope (Celestron 130 eq) with 5.2 inch (~132 mm) aperture with 650 mm focal length, Spherical mirror. And having 4mm, 10mm, 12.5mm, 20mm,20mm (erecting eyepiece), a 3x and 1.5x ...
Kavin Ishwaran's user avatar
3 votes
0 answers
59 views

Precision of orbital period of exoplanets vs solar system planets (Extrasolar Planets Encyclopedia)

I noticed that the Extrasolar Planets Encyclopedia lists the orbital period of L 98-59 b in days to 7 decimal places. Can astronomers really measure orbital period of exoplanets to greater precision ...
sno's user avatar
  • 920
1 vote
2 answers
256 views

How slow would you age on a double gravity planet?

How slow would you age on a double gravity planet? Gravity of the planet A is 10 units. If you are taken from planet A to planet B where gravity is double that of A, i.e. 20 units. How slowly would ...
Sazzad Hissain Khan's user avatar
2 votes
0 answers
55 views

Would Atlas Pro's prediction about the color of plant in Kepler-186F work as a biosignature to search for life?

The Atlas Pro video that prompted this question is this. Tl;dr: it is argued that due to the different spectrum of radiation emitted by Kepler-186 and what is known about the evolution of ...
Rubén Crespo's user avatar
9 votes
2 answers
2k views

What is the probability of life having developed or going to develop in our solar system another time?

I'm sorry I am not quite sure this question satisfies this point: Questions that are purely hypothetical, for example a question such as 'Could a black hole destroy the universe' or 'What if our ...
steros's user avatar
  • 199
2 votes
1 answer
119 views

Special case of rotation period

Rotation period is either prograde, like the Earth, or retrograde, like Venus. How likely is it for a body orbiting its parent object (either a planet around a star or a moon around a planet) to have ...
jkztd's user avatar
  • 463
0 votes
1 answer
79 views

Can the pebbles growth model be applied to the rotations of planetary systems? [duplicate]

I've just read the University of Amsterdam 2019 News item Pebbles determine the direction in which planets rotate (which links to R.G.Visser et al (2020) Spinning up planetary bodies by pebble ...
Deschele Schilder's user avatar
5 votes
3 answers
2k views

Moons with synchronous rotation in our solar system

Are all moons in our solar system rotating synchronously around their planet? If not, what are the criteria that some do and some don't? Many thanks for any insights!
VBA Pete's user avatar
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6 votes
1 answer
390 views

At high temperatures, do planets glow like blackbodies?

I've been messing around in Universe Sandbox for a while and noticed that as a planet heats up, it glows like a blackbody starting at ~4000 K. Is the simulation here accurate, or do very hot planets ...
WarpPrime's user avatar
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0 votes
0 answers
107 views

Longest and Shortest day of the year in all planets

Can we trace the longest and shortest day of the year in other planets of Solar system similar to earth planet i.e. Mars, Saturn, Venus, Jupiter, Mercury, Neptune, Uranus?
Prashant Akerkar's user avatar
1 vote
0 answers
56 views

Will a solidifying core inside a planet affect its appearance?

In this question it is said that Mars once had a liquid core that solidified. If the liquid has a smaller density than the solid, will this affect the outer parts of the planets? For example, if the ...
Deschele Schilder's user avatar
2 votes
0 answers
70 views

What would be the electric potential and the energy produced in a cable connecting two electronic devices on the magnetic poles of the earth? [closed]

The earth is a large magnet moving in the magnetic field of another large magnet the sun. And if we connect the two poles of the earth by a cable there would be energy and an electric potential in ...
Extrazlove's user avatar
1 vote
1 answer
151 views

Does the sun have a notable frame-dragging effect on the planets?

Frame-dragging is a general relativistic effect that can be imagined as the effect that the momentum of mass-energy has (the stress elements in the stress-energy tensor) on mass-energy in the ...
Deschele Schilder's user avatar
2 votes
1 answer
303 views

What does it mean for a planet to have an "icy" core?

My understanding of the physics of planets leans heavily on my understanding of the physics of stars - of course there are important differences. One important difference that I've found is the nature ...
Daddy Kropotkin's user avatar
4 votes
1 answer
233 views

Is this how stars’ right ascensions correlate to planets’ longitudes on a 2d map?

This is my first ever online question, so please bear with me: I’m working on an A1-sized map of at least 100 of the largest solar system bodies (henceforth just called ‘planets’, ignorning the IAU ...
DavidBriz's user avatar
1 vote
1 answer
77 views

Weight of a gas measured in Space and other planets of Solar System

I searched for how measure gas weight and about gases in space https://www.shutterstock.com/search/space+gases https://education.seattlepi.com/gases-found-outer-space-5888.html Will the weight of gas ...
Prashant Akerkar's user avatar
1 vote
0 answers
55 views

How likely are triple planet systems?

Is it likely to ever discover three planets of similar mass revolving around a common barycenter, or would such a system be too unstable? Such triple planet system would look like a triangle once in a ...
Giovanni's user avatar
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3 votes
0 answers
51 views

How to distinguish primary hosts (stars) and orbiting satellites (planets) and tertiary bodies (moons) by their mass and trajectory?

Suppose one has run a gravitational simulation of N bodies (has the mass, vector positions, vector velocities, etc for each body), but knows nothing a priori about ...
zeebeel's user avatar
  • 31
2 votes
2 answers
263 views

How close to a host star can a tidally locked planet be and its dark side still maintain a moderate temperature?

So, imagine an atmosphere-less planet, tidally locked to a sun-like star. How close to the star can the planet be before its dark side becomes too hot? I imagine that at some point the rocks on its ...
Anixx's user avatar
  • 1,255
6 votes
1 answer
70 views

Calculating the radial tidal amplitude on a planet from the fluid Love numbers

How do you calculate tidal amplitudes from the fluid Love numbers? In my course on planetary physics I saw an approximate expression for the displacement from equilibrium tide: $$\Big|\frac{V_T}{g}\...
theWrongAlice's user avatar
0 votes
0 answers
105 views

Converting Invariable plane to J2000 ecliptic

I've been following the answer given by Mike G here: How to calculate the orientation of planets at current epoch to get planets to have the correct orientation in my program, but all the angles are ...
nussun's user avatar
  • 1
-1 votes
1 answer
1k views

Maximum and minimum masses and sizes of giant planets?

What are the minimum & maximum masses and diameters of giant planets? Minimum end of the scale Earth has mass of 1 Earth mass and a mean radius of 6,371.0 kilometers, and thus a mean diameter of ...
M. A. Golding's user avatar
3 votes
0 answers
44 views

What is the theoretical maximum variability a pulsating red giant can have such that a habitable planet can stay habitable for long periods of time?

I was reading about red giants and came across this statement: Some research suggests that, during the evolution of a 1 M☉ star along the red-giant branch, it could harbor a habitable zone for ...
WarpPrime's user avatar
  • 6,613
2 votes
1 answer
467 views

What is the Milne-Eddington Approximation?

In this paper: Planet temperatures with surface cooling parameterized it states in the "radiation model" the following: The Eddington–Milne approximation relates $T_0$ and $T_e$ through the ...
Astavie's user avatar
  • 71
4 votes
1 answer
217 views

Questions on apparent motion of superior planets

Question Why is it that superior planets seem to oscillate up and down of the ecliptic, from the view of an observer on Earth, with a period equal to the planet's orbital period? Additionally, why do ...
William Jauntelle's user avatar
3 votes
1 answer
66 views

What is the longitude of the winter solstice for the various planets?

I am looking for data showing the longitude at which the various planets in the solar system reach their winter solstice. Where could I find this data?
magnolia1's user avatar

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