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 hasn't the "9th Planet" been detected already?
In the comments to this question, there was considerable doubt placed as to the subject of if the so called "9th planet" really exists. That wasn't really the intent of the previous question, so I ask ...
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Why do (most of) the planets rotate counterclockwise, i.e. the same way the Sun does?
Referring to the mechanisms explaining the solar system formation and to the initial rotation of the gaseous cloud that collapsed, I understand easily why the planets orbit the Sun the same way this ...
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Why do the planets in our solar system orbit in the same plane?
(Yes I'm excluding Pluto from this the same way it was excluded for not being a planet)
Observing the planets orbit of the Sun they all seem relatively planar and roughly all orbit along the same ...
user96
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How many planets are there in this solar system?
So, in school (that's a long time ago) they have been teaching us there are 9 planets in our solar system.
Mercury
Venus
Earth
Mars
Jupiter
Saturn
Uranus
Neptune
Pluto
But every now and then I keep ...
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How to calculate the expected surface temperature of a planet
I'm writing a program to generate solar systems but I'm having trouble calculating the expected temperature of a planet. I have found a formula to calculate this, but I haven't been able to get a ...
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What causes "North-South ambiguity" when doppler radar imaging a planet surface equator?
I'm having a hard time understanding why there would be this ambiguity. Also, why would this be not the case if the planet was viewed pole on?
Edit: "North South ambiguity" is a term used in ...
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9th planet location?
I've seen a number of news reports indicating there is likely a 9th planet in our Solar System, something with an orbital period of between 10k-20k years, that is 10 times Earth's mass. I haven't seen ...
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Does this smartphone photo show Mars just below the Sun?
I live in Essex, England (51.7678° N, 0.0878° E). On 25 July 2019 (hottest day ever in the UK, btw), 06:43 BST, I took this smartphone photo of the Sun. Is that white dot just below and left of the ...
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How are rogue planets discovered?
Planets are usually found by observing a star and waiting for the light level to drop when a planet passes in front of it, but what about rogue planets that don't have host stars?
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Why are orbits elliptical instead of circular?
Why do planets rotate around a star in a specific elliptical orbit with the star at one of it's foci? Why isn't the orbit a circle?
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What physical features determine if a planet is a major, minor or dwarf planet?
Like many, when I was growing up, we always were taught, hence always learned that there were 9 planets. However, recently, decisions were made and all of a sudden there were 8 major planets and a ...
user8
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Why are planets spherical?
I am a complete novice when it comes to astronomy, but someone asked me the above question casually. It seems as though planets are all roughly spherical, whereas other celestial bodies aren't ...
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Compute Planet's Apparent Visual Magnitude
In a hypothetical solar system there exist:
a sun of radius $r_s$ and absolute visual magnitude $V$
the Earth, with radius $r_e$ and distance from the sun of $1\,AU$
another planet, wit radius $r_p$, ...
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How did early estimates of a "potato radius" set 1 eV ~ GMμ/R and get 200 to 300 km?
@DavidHammen's answer explains that Goblin has roughly a potato radius and I can't believe I just wrote Goblin and potato in a serious question. That happened.
The linked paper; The Potato Radius: a ...
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Can the paper narrowing Solar System's barycentre to within 100m help find Planet Nine?
I've just read this recent news article, Astronomers Have Located The Centre of The Solar System to Within 100 Metres, reporting on a paper[1] that claims narrowing the Solar System barycentre to ...
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When will all eight planets in our solar system align?
Ignoring expansion of the universe, entropy, decaying orbits, and interference from any bodies colliding with or otherwise interfering with their orbits, will the eight planets known planets in our ...
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Open problems in astronomy that an amateur (with a PhD in some other field) would have a chance of solving?
What are some open problems in astronomy that an amateur would have a chance of solving? Suppose the amateur has a PhD in some other field, owns a basic telescope, a set of filters, diffraction ...
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Does the gravity of the planets affect the orbit of other planets in our solar system?
When one planet passes near another during its trip around the sun, does their gravitational pull is strong enough to disrupt noticeably each other's orbit ?
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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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Why does the planet Saturn have numerous (62) moons compared to the rest of the planets in the Solar System?
Saturn is a gas giant like Jupiter. It has everything from
tiny moonlets less than 1 kilometer across to the enormous Titan, which is larger than the planet Mercury. Saturn has 62 moons with ...
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Is there convection in Mars' mantle?
Mars is differentiated, with a core, a mantle and a crust. There are no (longer any) plate tectonics on Mars. Does this mean there is no convection in the mantle? Could there be convection in the ...
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Why do stars twinkle but planets don't [duplicate]
Many people say that stars twinkle because of Earth's atmosphere. However, the atmosphere is still there when we look at planets and don't see they twinkling.
Is there a clear scientific consensual ...
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Why are planets round? [duplicate]
I was studying our solar system and all celestial objects are depicted as round objects, including black holes.. worm holes as hollow cylinders as a pathway across two universes.. even the galaxy is ...
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Why don't we detect planets around OB stars and no terrestrial planets around A or early F stars?
Looking at an exoplanet database, I noticed that there are very few planets detected around main-sequence OBA stars, and most of them are gas giants/brown dwarfs. Why can't we detect low-mass planets ...
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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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What makes protoplanetary disks start rotating? (Initial energy needed to rotate)
Planets form from a protoplanetary disk that has been rotating around its star. The initial energy that makes them rotate really matters to me.
Why did the protoplanetary disk start rotating around ...
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Is there a upper limit to the number of planets orbiting a star?
Our sun has 8 planets orbiting as well as a number of dwarf planets. Are there any calculations that hint as to whether this number is close to some theoretical maximum value or are we simply an ...
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How did scientists determine an estimate of the number of planets greater than Sedna's size to exist in the Inner Oort Cloud?
In the article, New Dwarf Planet Found at Solar System's Edge, Hints at Possible Faraway 'Planet X' (Wall, 2014) where they report on research and observations performed by astronomers that discovered ...
user2449
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Orbital velocity of a planet - why is my calculation off by about 10%?
I am not sure if I am doing something wrong, or misunderstanding Reider and Kenworthy (2016).
I'm just trying to reproduce the orbital velocities listed in Table 1. The second paragraph of Section II ...
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What wavelength to best detect the "9th planet"?
We know that the reflected sunlight will make detecting the 9th planet very difficult in the visible light. Is there another band that will be more likely to detect it? What is the surface temperature ...
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Changes to Earth's orbit
Any time a spacecraft comes in close proximity to a planet and if the spacecraft has the right angle then it is able to use the planet's velocity to move itself further into space.
According to ...
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Can dark matter be found in the shape of planets, galaxies etc.?
If dark matter has gravity just like normal matter, does that mean it can also form planets, solar systems and so on?
Any answer will be appreciated.
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Is Jupiter a dwarf planet?
I know the question seems silly, but as far as I've understood, is this the definition of a dwarf planet:
circling around a star, and not being a star itself
having a round shape (otherwise every ...
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Do blue giants have a habitable zone?
Or would the planet(s) need to be too far away for life to exist?
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Years, months, days, and ... weeks?
Why do we divide time into weeks? Is there any celestial reason why humans do this?
one year: earth revolution around the sun
one month: moon revolution around the earth
one week: 7 days = ???
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How small can a planet be and still have Earth-like gravity?
A planet made from denser material than Earth might have equal gravity to Earth but a smaller radius. How small can a planet be and still have Earth gravity?
Ideally it should be habitable by humans, ...
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3 years later, how strong is the evidence for planet 9?
I came across post in quora where somebody said that "most astronomers no longer think Planet 9 exists" and being somewhat shocked by that, I did a google search and found a fairly recent article that ...
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How was the hypothetical ninth planet kicked so far out of the Solar System?
I was reading this article on science news and ran into the following statement:
Such a remote super-Earth probably originated closer to the sun only to be kicked out by the other giant planets ...
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"Pluto Time" for any solar system body
A while back NASA made a site called Pluto Time, where you can enter your address and find that "...moment near dawn and dusk each day, where the illumination on Earth matches that of high noon on ...
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Are there any known planets whose axis is oriented such that one pole always faces its star?
Earth rotates around the sun and around its axis (A North, South axis) giving us days, nights and seasons.
Are there any known planets that rotate with an axis pointing toward its sun so that one ...
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Why not us interferometry to take a picture of Pluto?
Interferometry is among the best ways (if not, the best way!) to have an image of a very distant object.
Recently a picture of the black hole at the center of M87 was released. It is the result of ...
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What's the name for [the other kind of planet] in a binary star system?
This XKCD what-if talks about rainbows on planets in a binary star system. It points out that there are two types:
circumbinary planets, where the planet orbits far from and around both stars
[the ...
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Why can we see the Pillars of Creation, but not Proxima B?
I was wondering how is it that we can see the Pillars of Creation (I know they're no longer there too) which are labeled as 6,500 light years away from earth and yet Proxima B is labeled at just 4.2 ...
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Maximum and minimum gas giant & ice giant densities
I'm working on a star system generator for a game; I'd like its results to be plausible but they needn't be super-realistic. I've got the orbital distances and masses of each body in the system, and ...
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Is Uranus the farthest object in Solar System that you can see with naked eyes?
The following text is from this article:
The fact is, even at its brightest, Uranus is still quite faint. It’s barely perceptible as a dim speck of light to the unaided eye, even under dark skies. At ...
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Color of planets
I am developing an astronomy software and need to know the color of each planet in the Solar System, when observed with the naked eye. I cannot find that information after googling for a while. Is ...
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Planets classification by density
In our Solar system, the density of major planets varies from 0.7 g/cm3 (Saturn) to 5.5 g/cm3 (Earth).
For exoplanets, the density varies from very low (0.03 g/cm3 for Kepler-51x) to very high (77.7 ...
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Brown dwarfs and planets
As far as I know, a brown dwarf is a 'star' whose core never underwent a fusion reaction, so it never became a star.
So I was wondering if, apart from orbiting a star, is there any difference ...
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What is the axial tilt of a planet measured relative to?
I am very much a beginner on the astronomy front but I understand about planets having different axial tilts, hence why Venus turns the opposite direction from the Earth and Uranus turns sideways.
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