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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How un-dense can a terrestrial planet get before it turns into a mini-Neptune?

EDIT: well, now I have more For reference: A terrestrial planet is a planet that is made out of silicates and metals. A Mini-Neptune is, as far as I know, the smallest type of giant planet (arguably,...
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What is precision of planet periods data?

Wikipedia gives $10759.22$ days for sidereal period of Saturn. I have calculated a period from de441_part-1.bsp and obtained $10736.247\bar{2}$ days. Why such a big difference? Which is more accurate? ...
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If Planet 9 is a primordial black hole with a mass of 5 Earth, is it possible to detect it in a ground telescope? What should we seek in this case? [duplicate]

If planet 9 is not a planet but a black hole how can we find it? Can we see gravitational lense or infrared/gamma light?
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How long would it take to realize there are "star-like objects" (i.e. planets) that change position in respect to the "fixed stars"?

If you were using unaided observations and were unfamiliar with astronomy (and maybe just pen and paper for recording anything), how long should it take to notice that Mercury, Venus, Mars, Jupiter ...
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Best lens for a beginner

Just bought a Celestron StarSense Explorer DX 130AZ for my son. What is the best lens to use for viewing planets? What are some easy tips for him, to help explorer his passion? He has the 25mm and ...
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When might Rowan-Robinson's planet be discovered or disproved?

A month ago Michael Rowan-Robinson discovered three dots on old images of the sky which may or may not be an undiscovered planet (that's not identical to Brown's and Batigyn's hypothetical planet). I ...
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Could stars like S2 near the galaxy's center have planets in a stable orbit?

I read about one of the stars orbiting Sagittarius A* and according to Wikipedia, it reaches a maximum speed of 0.03c during its orbit. Would this (or any other factor) make it impossible for a planet ...
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Was the young Sun cooler or hotter than it is today?

Generally, astrophysicists say that the young Sun was only about 70% as warm as today, which leads to the alleged 'Faint young Sun paradox' about how a young Earth could have been as warm as it (again,...
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At what rate does the right ascension and declination of a planet, the sun and moon change per hour?

I'm currently building a web app and am getting the RA's and Dec's of solar system objects based on date and time chosen by the user. Then using the gmst for 0 hours of the date, the app calculates ...
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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-...
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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 ...
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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'...
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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 $...
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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 ...
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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 ...
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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'...
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1answer
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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 ...
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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 ...
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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 ...
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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 ...
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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?
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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1answer
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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 ...
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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. ...
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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 ...
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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 ...
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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 ...
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Is life possible on other celestial objects (apart from planets) even theoretically? [closed]

For example, asteroids, comets, stars, heliosphere etc?
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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 ...
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1answer
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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What is the size of the universe? [duplicate]

Will as a result of the continuation of technological progress in the twenty-first century more perfect telescopes or other astronomical instruments that will allow to know what is on the surface of ...
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1answer
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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 ...
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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 ...
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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!
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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 ...
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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?
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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 ...
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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 ...
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1answer
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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 ...
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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 ...
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1answer
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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 ...
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1answer
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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 ...

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