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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What kinds of stars have viable habitable zones other than G-type stars, and what would life be like orbiting them?

What would foliage, landscape, and quality of life on dwarf stars and blue stars? Would it be possible for a human to live without high-tech devices and such?
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8 votes
1 answer
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Binoculars 10x50 in light polluted place

I think to buy cheap 10x50 binoculars for astronomy observations. My leaving area is light polluted, I can see only bright stars and planets in naked eye. Will I can with this binoculars observe ...
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8 votes
3 answers
2k views

Planets looks like normal stars when I see them using telescope

I've been trying to see planets using my 114 mm (aperture) f=900 mm telescope. For the moon, I got very good quality pictures, but when I try to see planets they just appear to be as if I'm looking at ...
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0 votes
1 answer
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Would an accumulation of dust in a planet's L1 Lagrange point plausibly obscure it from Earth?

I'm designing a hypothetical newly discovered planet in our solar system that has an ecosystem comparable to Earth's that supports intelligent life. The explanation given for the planet remaining ...
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1 vote
3 answers
230 views

Is there a Lagrange point between the earth and the moon?

Is there a Lagrange point between the earth and moon where a space station could sit forever without orbiting around either? Just curious, but it seems like a place like that would be perfect for ...
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1 vote
0 answers
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What are the time periods of precession of equinoxes of other planets?

Earth has a time period of 26000 years approximately for precession of its equinoxes. What are the time periods of precession of equinoxes of other planets?
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4 votes
3 answers
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Why do most dwarf planets have mass comparable to moon?

It was quite interesting to spot that most dwarf planets have masses close to that of our moon (if we let an error to fluctuate within two orders of magnitude). Why it is so? Is there any common ...
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5 votes
1 answer
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If the Earth became tidally locked with the moon, would that last forever?

If the Earth and the moon became tidally locked, would this last theoretically forever (assuming no external gravitational force modifies their orbits, for example, ignoring the effects caused by the ...
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8 votes
1 answer
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How am I supposed to locate the planets Uranus and Neptune with a 70 mm f/5.7 refractor?

I can locate all of the planets other than Uranus and Neptune. This is mainly because they are very dim and I live where there is just enough light pollution so that I can't spot them. I have a Gysker ...
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3 votes
0 answers
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Why aren't there sulfuric acid seas on Venus?

It's commonly known that sulfuric acid rain doesn't reach Venus' surface. It evaporates instead because the surface it too hot. But considering how high the pressure at the surface (9.3 MPa), shouldn'...
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1 vote
2 answers
103 views

Could a magnetosphere be created for Venus by recreated by spinning-up the planet to a 24 hour day?

If Venus in it is current state, started rotating at the same rate as Earths 24hrs rotation, would it develop a magnetic field of roughly the same strength as Earth's? If so, would that help in any ...
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17 votes
3 answers
5k views

If planets are ellipsoids why don't we have 3 diameters?

We know that each ellipsoid has 3 diameters named $2a$, $2b$, and $2c$. The Earth and all planets, in general, are ellipsoids (Saturn is the best example because it's the most oblate planet in the ...
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4 votes
3 answers
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How do rocky planet break up? Would they fragment into "a gazillion" rocky pieces pieces, or crack open like an egg?

I remember seeing a movie (probably star wars) where this bad guy (Darth Vader) shoots a superb laser (Death star) to obliterate a populated planet, Alderaan (how inhumane). The problem is, the planet ...
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12 votes
1 answer
2k views

Daylight hours on Titan?

I still cannot seem to wrap my head around Titan's day and night based off of math. From what I understand, Titan has a day of 16 earth days (384 hours) in which it circles Saturn once (its day and ...
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3 votes
1 answer
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Accurate formula for calculating the mass of an exoplanet using the transit method

A friend and I did some work on exoplanets with the help of a research institute (IEEC in Spain) for a major high school project. What we did was to "redetect" the exoplanet XO-6b through ...
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1 vote
2 answers
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Planet's distance data from JPL Horizons - Mars Curiosity mission

I am looking for distance measurement in AU between planets and Earth. E.g. For Mars, Current distance, or distance of Mars from Earth at any given datetime, along with minimum (closest approach), ...
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-1 votes
1 answer
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Can a destroyed earth reform into another habitable planet?

Let's say a planet-sized object collide with earth, disintegrate it, then reform at the same orbit as earth. Will it eventually formed into a habitable, life-supporting planet with living organism?
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1 answer
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What would the temperature be on the surface of Sirius B [closed]

If Sirius B was a planet like Earth and not a white dwarf star what would the temperature be on the surface of Sirius B at its nearest and furthest distance? 8.2 AU to 31.5 AU EDIT: I want to know if ...
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-2 votes
1 answer
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Is it possible that Planet 9 was thrown out of the Solar System? [duplicate]

Is it possible that this planet changed other planet orbits (from which we assume that it exists) but then was thrown out of the Solar System in past when Sun was close to some other star? And it ...
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2 votes
1 answer
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Earth-Mars-Moon or No Moon Barycenter Orbit Possible?

Could an object of sufficient mass deflect Mars so that it ends up stably orbiting an Earth-Mars-Moon barycenter? What would the distances eventually become between each orbiting body? What if the ...
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6 votes
0 answers
143 views

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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2 votes
1 answer
119 views

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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0 votes
0 answers
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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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3 votes
1 answer
116 views

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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8 votes
1 answer
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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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7 votes
2 answers
121 views

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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2 votes
3 answers
101 views

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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1 vote
1 answer
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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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2 votes
0 answers
37 views

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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1 vote
2 answers
87 views

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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8 votes
4 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'...
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1 vote
1 answer
84 views

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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4 votes
2 answers
105 views

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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4 votes
2 answers
94 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 ...
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0 votes
1 answer
92 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'...
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1 vote
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 ...
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0 votes
1 answer
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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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1 vote
0 answers
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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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31 votes
2 answers
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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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0 votes
1 answer
62 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?
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12 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 ...
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4 votes
1 answer
149 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 ...
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7 votes
1 answer
871 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 ...
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0 votes
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 ...
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1 vote
1 answer
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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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6 votes
1 answer
81 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 ...
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3 votes
2 answers
910 views

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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2 votes
0 answers
39 views

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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3 votes
1 answer
90 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 ...
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