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Questions tagged [gravity]

Questions regarding the attractive force which exists between any two bodies of matter.

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How does gravity affect pressure under water?

How different would being under water in Europa differ from being under water on Earth? Would it be possible to dive deeper on Europa with a submarine than on Earth and by how much?
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Why don’t we feel the Earth rotating beneath us?

I’m not sure all of the details in the experiment but basically it went as follows. Someone marked their location of take off in a hot air balloon and went straight up in the air. They stayed ...
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Black hole, escape velocity, going up?

I do know nothing can escape a black hole, and I understand popsci explanation of geodesics of space-time around and inside the event horizon. I however have some trouble with following thought ...
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Could a moon be passed from one planet's orbit to another?

Like if you had two planets that had a close orbital path could the moon be pulled away from the first planet?
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66 views

What is the smallest possible planet with same sea level atmospheric pressure as Earth? [closed]

Suppose there is a planet made of pure tungsten (a quite common and heavy element), with perfect spherical shape. Which should be its radius so that the air pressure and ground/sea level is the same ...
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1answer
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The specifics of two Earth-like worlds orbiting each other? [closed]

I'm currently looking into writing a story or two set on twin worlds, which I came to find out in my research is apparently not a new idea (Double planets? Rocheworlds? Am I close?). But I want it ...
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Since gravity is like an indent on a piece of paper (the space/time matrix) to a marble, can the black hole eventually suck in the matrix?

Can a black hole suck in time? People claim that if you were to put a bowling ball on a trampoline and rolled much smaller balls through the deppression, some would stay in "orbit", some would roll ...
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Is there a limit to how fast spacetime can bend/warp around an accelerating object?

If in the future a spaceship can accelerate to nearly the speed of light, will it encounter any kind of resistance/drag from the spacetime in front of it not being able to bend/warp fast enough around ...
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Could the Moon sit on the Earth?

Let say that the Earth's Moon was knocked out of orbit and landed on the Earth with some damage but not world ending. Would Earth's atmosphere envelop to include the Moon? Would the moon sink into the ...
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1answer
60 views

How dependent is Earth is with the other Planets' gravity? [duplicate]

How would the Earth be affected if the Moon was destroyed as far as our orbit around the Sun? What if Mars or Jupiter was destroyed?
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1answer
62 views

Does time dilation increase within overlapping gravitational fields?

If a spaceship was to travel to the barycenter of a binary star (the stars having identical size and mass) and come to a stop there, would the people on board this spaceship find that time is moving ...
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Expansion ofthe Universe [duplicate]

If the universe is expanding how come Andromeda is heading for us? In isolated spatial areas does gravity overcome universal expansion? What is the gravitational force between us and Andromeda?
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Astrophysical Jet Size?

I am wondering about what is the estimated size of astrophysical jet that shoots out from a black hole, I don’t know if it is determined by the size of a black hole. What would classify a black hole ...
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Space curvature and its rotation

As I learn, the gravity is caused by the spacetime curvature. Is there any gravitational/magnetic field that really exists around the Earth, or any other planets? Since the planets/stars rotate, does ...
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2answers
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Why does earth not collide with the sun? [duplicate]

Gravity is most accurately described by the general theory of relativity (proposed by Albert Einstein in 1915) which describes gravity not as a force, but as a consequence of the curvature of ...
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1answer
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Could dark matter be wrong? [duplicate]

As I understand, the evidence for dark matter is the observation of the gravitational dynamics of objects around the size of galaxies and above. They move in a way such that the equations imply there ...
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3answers
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Is there any orbit at which the Roche limit can be “felt”?

Do any of the planets have a Roche limit that is strong enough to be felt by an astronaut whilst in orbit? Bonus: Would change in density along the surface of Jupiter or the star cause ripples in ...
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How come moon's difference in thickness between sides does not create an unbalance on its mass?

I've just found out that moon's dark side is 30 miles thicker then the closer side to the Earth. So I'm wondering about moon's mass. How come it's still balanced? Supposing the far side is indeed ...
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1answer
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Can gravity be amplified by other celestial bodies in its vicinity?

I`m wondering if the gravitational pull from earth that should be constant around the planet, will get amplified by a celestial body like the moon orbiting the earth?
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Universe Sandbox 2 accurate representation of gravity

I've been playing Universe Sandbox for a while now and I have never been able to make a near Earth asteroid collide with it. By "make" I mean, simulating billions of years of known, near Earth objects ...
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How does the gravity of one planet affect the velocity of other planets?

If there was a massive enough planet outside of earth's orbit to affect it, how would the earth's velocity change? I know it would be small, but would the velocity increase or decrease?
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1answer
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Could two planetesimals orbit a dense object and share an atmosphere?

Could two objects be caught into an orbit around some kind of dense object, perhaps a rogue planet. Could they share an atmosphere.
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1answer
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Physical measurements and celerity of black hole mergers?

LIGO detected a black hole merger for bh's of about 30 solar masses, with a schwartzchild radii of about 20km. Were the gravity waves generated by masses distanced by a few microns or a few ...
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Why do neutron stars collide instead of just revolving around each other like planets revolve around the Sun?

We know about events like two neutron star colliding and resulting in a black hole, also collision of black holes, and collision of galaxies. But we never see a satellite such as a moon colliding with ...
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1answer
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Are the planets in our solar system in free fall?

If I’m correct, the International Space Station is in free fall, but is moving fast enough to keep it’s position. Assuming that is true, does that mean that some/all planets orbiting the Sun are in ...
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1answer
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How far out can the sun keep celestial objects revolving?

Astronomers define the Solar System as the distance under the influence of gravity from the Sun. I read that the Oort cloud is probably the farthest object that surrounds the sun. The sphere of this ...
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Does center of gravity of Solar system influence intensity of space rays reaching earth, space dust, speed of earth rotation?

I found an interesting article, claiming very interesting things. But I cannot find any trust-worty sources confirming such bold claims. Maybe someone came across some solid proof? 1) Center of ...
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0answers
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Great attractor is doing the big crunch? [closed]

Laniakea and other super clusters are moving towards shapely super cluster . Even the Great Attractor is moving towards it. Isn't it all about the Big Crunch?
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When the asteroid hit the earth 65 mya did the earth's gravity pull change? By how much?

When the asteroid hit the earth 65 million years ago, did the earth's gravity pull change? By how much?
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Inconsistent Precession (Apsidal Rotation) Rate formulae for circular Clairaultian Orbits

TWO CLAIRAULTIAN GRAVITATIONAL FORMULAE Wells 2011/2016 refers to two well-known patterns of centripetal acceleration which (when applied in a Euclidean-Newtonian orbital system) produce "perihelion ...
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1answer
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Can a star eat a black hole?

I know there are stars much larger than the sun and that we've discovered "small" black holes, so, let's say that the Pistol Star, which is at least 80x the mass of the sun, and the smallest known ...
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Can anything escape a black hole or not? [duplicate]

I'm not a professional astronomer or physicist, though the fields greatly interest me. Please keep this in mind if the following sounds like a stupid question. In virtually every documentary I've ...
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2answers
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Roche limit - calculation with centrifugal forces

Let's assume there is a small natural satellite oribiting a massive planet. The satellite rotates synchronously (revolution period = orbital period) on a circular orbit, both bodies are homogenous and ...
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Gravity on a right rectangular prism? [closed]

Let's assume there is a right rectangular prism floating about in space, what would the gravity be like across its 6 flat surfaces? What gravity would you experience if you set foot on the rectangular ...
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Do other planets affect the Earth?

Let say Mercury, Venus, the Moon were all in alignment between the Earth and Sun. They are all closest to each other in respective elliptical orbit. On the other side of the Sun you have the rest of ...
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Can Earth be spun like a magnet?

Could an asteroid or a rogue planet have enough magnetism and/or gravity to spin the Earth near the speed in which they are passing by Earth?
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1answer
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Can you simulate artificial gravity by using an electromagnetic field?

If you create a electromagnetic field under a surface could you then create artificial gravity effect by wearing magnetized clothing and shoes? Or could you bombard objects that you want to ...
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How does space time differ between galaxies? [duplicate]

Does the gravity wells differ enough between galaxies to have different speeds in space time? How much slower in space time would the biggest galaxy have compared to the Milky Way?
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Are there currently any planned or proposed missions to measure the gravitational fields of other planets in our solar system?

I just recently found out about the GRACE Nasa mission which basically mapped out the gravitational anomalies of earth as well as serving extensively in the study of earths geology and the movement of ...
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How does the size of a naked black hole effect its photon sphere?

What effect does the size of a black hole have on the size or density photon sphere and proximity to the horizon? If a person is in space looking at 2 black holes (one of them big and the other ...
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1answer
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How would you relate the respective solar gravitational pulls of two planets?

I was asked this question: How much weaker is the gravitational pull of the Sun on Neptune at 30 AU, than it is on Earth at 1 AU? How would I even begin to determine this?
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Gravitational eddies across the galaxy?

I read about natural gravitational eddies that travel in a wave that black holes have. They also have a strong magnetic field. Does those eddies follow magnetic field lines of the rotating black hole? ...
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1answer
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What is the light that we see from a neutron star come from?

What hold the electrons in orbit? Is it gravity or the atomic attraction between the protons and neutrons? I asked this question on Physics SE I hope I improved on the quality enough to do better ...
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2answers
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Dark matter virtual objects hypothesis [closed]

I've hypothesized for many years in my head that dark matter are the gravitational after effects of objects that have exploded. My understanding of physics is that when an object explodes, its center ...
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Does Uranus have a stronger gravitational pull on its moons than Earth does?

I've read that Uranus has a lower surface gravity due to its lower density than Earth. However, does this mean Uranus has a weaker pull on its moons than Earth does for the same reason?
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Do unattached objects contribute to a planet's gravity?

If you could measure Earth's gravity with infinite precision, and did so both with Earth and its full population, and Earth with no people, would there be a direct difference in gravity? Is this even ...
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4answers
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Why does gravity make everything round?

I am studying ways to make an anti-gravity machine (!!). I believe it can be done, or theoretically be done using gravity itself as a "force" that pushes outwards instead of inwards. A similar ...
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5answers
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Theoretical sudden appearance of a black hole in BBC drama show *spoiler warning*

I asked this on the ‘movies’ stackexchange site but they suggested I ask here, it’s a purely hypothetical query based on a BBC drama show called ‘Hard Sun’, feel free to kill the question if it’s ...
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Explain to a 4-year old why people below the equator are not tilted or suspended upside down

So I just bought a globe for my extremely inquisitive soon to be 4-year old son. He knows the very basics of the solar system and knows that we live on planet Earth and also knows the concept of ...
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1answer
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Behaviour of black holes

This question could be strictly linked to my another question related to black holes. It’s known that the horizon event is a place where dust,star components are ready to be incorporated to the ...