Questions tagged [planets]

Celestial body that orbits following an elliptical path around a star or stellar remnant.

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What occurs as centripetal acceleration nears the gravitational field of a planet?

If a planet is generating centripetal acceleration close to its own gravitational field at the equator, what occurs to the weight of someone on the equator? What happens if centripetal acceleration is ...
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What effect will a space-elevator have on Earth's rotational speed?

If you (or e.g. a skater) spin on the spot with your arms outstretched you spin at a given speed, but when you retract your arms you spin much faster, extending your arms again will slow the spin down....
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Motions of planets from a non-rotating earth frame

Suppose you are hovering just above the earth at a fixed distance such that you are not rotating with it (the earth is obviously rotating about its own diametrical axis) but you are orbiting the sun ...
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What would the chemical and atomic effects of an antimatter star be upon a normal matter artificial planetoid? (Thought experiment)

Setting aside all the challenges of actually achieving such a thing, and as a thought experiment, what would the chemical and atomic effects of an antimatter star be upon a normal matter artificial ...
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How do molecules absorb heat?

How do molecules absorb and retain heat, and how is that heat able to still affect nearby molecules? On Venus there is a green-house effect where the large, dense Carbon-Dioxide atmosphere absorbs ...
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What would the effect of an antimatter star be upon a normal matter planet? (Thought experiment)

Based on the answers from this question: Would the solar wind from an antimatter star be any different from a non-antimatter star?, it seems that an antimatter Sol type star would conduct fusion ...
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What is the difference between the nutation of the Earth and the Chandler woble?

I have been trying to understand the different things about the earth's rotation and revolution. But the terms Chandler wobble and nutation seem alike yet have different time periods.
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Could a planet experiencing tidal locking have a habitable area?

I wonder if it would be possible that, on a planet that always shows the same face towards the sun, there is a habitable area for some life-form similar to that of the Earth. I guess, since one face ...
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Where does the radial velocity component come from?

Any object under the influence of a central force will have two components of velocities: Radial and rotational I understand that the rotational velocity is there due to the centripetal force. But ...
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What would the collision between a (large) solid planet and a gas giant be like?

Assuming a Jupiter-like planet and an Earth-like planet (Except, say... half the mass of Jupiter), what would happen when the two collide? For clarification: What would the actual collision be like? ...
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If planet like Jupiter is massive enough to hold hydrogen with its gravity is it bound to become a star?

I have been reading about Jupiter as of late and reason I am asking is if Jupiter has strong enough gravity to pull hydrogen to itself then it should be only matter of time when it will acquire enough ...
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Can we rule out life swimming in the oceans of Europa and Enceladus on the basis of a lack of available energy?

Jupiter's moon Europa and Saturn's moon Enceladus (and several other moons too) have large subsurface oceans of liquid water, an ingredient considered essential for life. These two moons occasionally ...
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Why is Jupiter's ring system so faint?

Planetary ring systems are formed when asteroids, comets, or any other large objects pass too close to the planet and are torn apart by the planet's gravity [1]. Jupiter is often called the "punching ...
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How does Planet 9's perihelion and aphelion affect the Kuiper belt objects?

Assuming that the existence of Planet 9 is confirmed and it really exists, how does it affect the orbits of the Kuiper belt objects? My understanding is that the discovery came in part from the ...
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How deep must Earth's ocean be to form Ice VII on bottom?

Is there way to tell how deep must Earth's ocean be to form Ice VII on bottom? Or is it impossible because of our planet is too small? As I know, in 11.5km Mariana Trench there is 108 MPa and to form ...
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Is it possible to prove that planets should be approximately spherical using the calculus of variations?

Is it possible to use the Lagrangian formalism involving physical terms to answer the question of why all planets are approximately spherical? Let's assume that a planet is 'born' when lots of ...
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Can dark matter explain the unusual orbit of transnettunian objects? [closed]

While we are struggling to find an hypothetical planet 9 to explain the unusual orbit of transnettunian objects, I was wondering if it could be just dark matter. We know that the universe is mostly ...
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Is space-time fabric around Uranus tilted?

I am completely new in this field, so please pardon me if I am asking something which makes no sense at all :) The Situation: According to Einstein's theory of relativity, there is a 4th dimension ...
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What's the biggest cube you could have before gravity rounded it?

I took this question from Quora because it seems interesting and this community would have some fun with it. I would assume that one would use the modulus formulas for force to counteract the gravity, ...
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When a planet is heated through gravitational pull, where is the energy taken from?

Jupiters moon Io is heated through the gravitational pull of Jupiter, but when Io is heated because of this, where does that energy come from? How does conservation of energy work for this effect, ...
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Weight at Poles and Equator Wrong?

Recently, I was thinking about the acceleration due to gravity on Earth when I remembered that I was taught that you weigh less at the equator because a fictitious centrifugal force "throws" you off ...
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Recent/More accurate rotation velocity measurement?

I've been researching for papers for hours and can't seem to find this. Where can I find the most accurate equatorial rotational velocity measurement for Mars?
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Do all the planets in our solar system orbit the sun in the same direction and in the same plane?

Do all the planets in our solar system orbit the sun in the same direction and in the same plane? (as in a flat orbit if you are looking from "above")
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Ever looming shadow

If I'm not mistaken the reason the moon eclipses the sun is because the ratio of distance to size, in regards to the moon and sun, is 1:1. And is it not also true that the reason we only ever see one ...
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Planets and Pluto? Neptune?

If one of the rules to be a planet is that it needs to clear ALL objects from their orbit, does this also make Neptune a non-planet? Since it has thus far failed to clear Pluto from it's orbit. Or ...
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Is the notion of 'weight of Earth' meaningless?

I am not talking about the distinction between mass and weight, just the concept of 'weight'. In University physics (book by Young & Freedman, 14th Ed.) it is given that the weight of an object ...
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Does frame-dragging affect planets?

The question has come up many times as to why the planets in our solar system lie in essentially the same plane. The most common answer is that they started out that way due to the accretion disk ...
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Equator water pipeline flow at sea level?

If a water pipeline was built at sea level eg. Gulf of Mexico and the other end was at sea level in southern Chile, then the pipeline was primed with pumps, would the water then gravity feed and flow ...
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What exactly will happen if a small planet collides with Earth?

This is a video of a simulation of Ceres (a dwarf planet) hitting Earth at 2000km/s. What strikes me the most, is how fast the shockwave is moving. It takes about 6 minutes for the shockwave to pass ...
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On a planet with winds faster than sound, what would it sound like?

I'm watching a Youtube video of the strangest planets and some of them have atmospheres/winds that constantly go at like 20x the speed of sound, ex: HD 189733-b .On earth, fast winds is actually ...
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Confusion about a claim in the “Brief History of Time” by Hawking

In the first chapter, while talking about how Aristotle was able to conclude that the Earth is spherical, Hawking says that had the Earth been a flat disk the shadow of the on the Earth on the moon ...
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Why Earth’s crust is max 100 kms wheras Moon and Mars have much thicker ones?

We know that the Earth’ mantle and core are hot, whereas the crust has cooled down. The cooling process of the 4,5 billion years of the Earth’ exisence resulted a crust of between 50 and 100 kms. ...
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Ptolemaic system parameters

I recently learned about the Ptolemaic system, which seems pretty accurate. There is even a simulator on the Internet: https://astro.unl.edu/naap/ssm/animations/ptolemaic.html You can see that there ...
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Why doesn't Venus have a magnetic field? How does the speed of rotation affect the magnetic field of a planet?

Why doesn't Venus have a magnetic field? How does the speed of rotation affect the magnetic field of a planet?
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Can a planemo turn into a star?

I read this question Why is planet CFBDSIR2149-0403 hot? and wonder what will happen to this "planemo". Will it attract more mass as it flows around in the gas clouds in space and eventually light ...
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How hot can the surface of a planet be?

I just read this article https://edition.cnn.com/2018/07/02/world/newborn-planet-image-study/index.html and noticed that the astronomers estimates the surface temperature of the planet to 1000 °C. ...
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Local temperature equation for a planet

After seeing in science fiction too many planets with two suns that look too much like a geocentric system, I'm trying for my own amusement to understand if it's really possible to have a planet with ...
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Mars longitude reference?

Platforms like NASA's JPL HORIZONS web-interface for solar system dynamics often have obtainable parameters like sub-solar or sub-terrestrial longitude for a given time and celestial object. (example: ...
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Uranus: The Spin

In his prog. , on the outer planets, Brian Cox stated that Uranus spins on its side because it once endured an interplanetary collision. Such a cataclysm would normally be devastating for both ...
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Is there a maximum distance from a planet that a moon can orbit?

Given a planet that orbits a star, and a moon that orbits that planet, is it possible to define a maximum orbital radius of that moon, beyond which the moon would no longer orbit the planet, but the ...
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If the mass of the Earth is decreasing by sending debris in space, does its angular momentum also decrease? [duplicate]

We are sending huge amount of debris into space from earth, and also very heavy satellites and rockets, then the mass of earth must be decreasing over time. If the mass will decrease, then ...
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Jupiter & Saturn

In his prog. on Jupiter, Brian Cox stated that the complex gravitational interplay, between Jupiter & Saturn, prevented Jupiter from drifting through the Asteroid Belt, and approaching our part of ...
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Bad value for sphere of influence with Venus [closed]

I would like to get value of sphere of influence than Wikipedia for Venus: on https://en.wikipedia.org/wiki/Sphere_of_influence_%28astrodynamics%29 It is indicated for Venus: $S_{\text{OI}}=0.616\,\...
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Mathematically calculate if a Planet is in Retrograde

How do you mathematically calculate if a Planet is in Retrograde when you are given both the Earth and the Planet Keplerian Elements value and rate? Keplerian Elements are: a - Semi-Major Axis; e - ...
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How does the Earth remain in its shape?

I know only stars do nuclear fusion to keeps its shape from gravity. Then what about the Earth? Earth doesn't do nuclear fusion. How does the Earth keep its shape even though the gravity keeps pushing ...
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How does the gravitational acceleration on a surface of planet change, if its radius shrinks while retaining the same mass? [closed]

If the radius of the earth were to shrink by $1$% while its mass remained the same, then how would the acceleration due to gravity on the earth's surface increase by $2$%?
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How to integrate acceleration due to gravity with height? [duplicate]

If I project a body at a very large velocity such that it reaches a height h which is comparable to Earth's radius, then how to derive an equation for 'h' in terms of initial velocity 'u' and other ...
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Do planets in elliptical orbits exhibit constant magnitudes of acceleration in their orbits?

I'm trying to reason through a problem. Consider Jupiter, which orbits the sun in an elliptical path. Is the magnitude of its acceleration constant throughout its orbit? My reasoning leads me to ...
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Relativistic space rocks. Are they possible?

I was thinking that the Universe is full of extreme events. Colliding galaxies, exploding stars, colliding planets (like in one of models of our Moon formation), colliding black holes... Can it be ...
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How is sound affected by gravity?

How would sound be different on a planet with a stronger gravitational field? My reasoning leads to sounds of the same wavelength having higher frequencies - is this correct?