Questions tagged [gravity]
Questions regarding the attractive force which exists between any two bodies of matter.
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Could it have been possible for the Moon to be split without any observable effect on Earth?
Before asking my question, I'd like to clarify why I'm asking about something so absurd. A supersitious claim has been bought to me that in the past, the moon was split and seperated as a sign. My ...
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The possibility of rapidly changing the Earths orbit via a passing astronomical object
I assume that the Earth could be “gently” (without colossal tidal or volcanic catastrophe) displaced by a passing extra solar star, brown dwarf or planet and end up perhaps 10% further away from the ...
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Matter falling into a black hole [duplicate]
Watching a science show, I was told that if I watch matter falling into a BH, I'd never see it crossing the event horizon due to time dilation (or rather, it will take more time than the universe ...
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1answer
105 views
Is a literal instance of Russell's teapot possible?
Much has been said about Russell's teapot, and I accept as obvious that a teapot would be too small to be detectable in an orbit around the Sun by any reasonable method today, or by any method that ...
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1answer
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Do the Bullet Cluster remnants prove that dark matter consists out of particles?
Some time ago the remnants of a collision between two collections of stars were discovered. These remnants are called the Bullet Cluster:
The color blue (non-visible in reality) represents the ...
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How is it possible that Saturn's gravitational acceleration felt by Mimas is stronger than Mimas' own surface gravity?
The surface gravity on Mimas is $≈ 0.063\text{ m}/\text{s}^2$ and Saturn's gravitational acceleration at the distance of Mimas' orbit is:
$$\frac{{GM}}{{r}^2} = \frac{{6.674 \times 10^{-11} \times 568....
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Why does time pass faster in moon than the earth?
One of my friends said that,
time passes faster in moon than the earth
Why does time pass faster on the moon than on the earth?
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Can two heavy objects circling around their C.M. be separated because of the speed of gravity?
Imagine two massive objects, with the same mass (M) circling around their center of mass (C.M.). Let's assume that the distance between them is 1 light hour. Don´t the two bodies get accelerated and ...
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Instantaneous gravity in equation of motion for ephemerides calculation
The equation of motion used for the calculation of orbits of solar system objects (Eq(27) in https://ipnpr.jpl.nasa.gov/progress_report/42-196/196C.pdf ) is formulated in terms of instantaneous ...
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What is 'surface acceleration' of a planet or other body? As opposed to its 'g' (gravity)?
The Mars Fact Sheet at NASA (their NSSDC or NSSDCA section, whatever that means) lists a value for 'surface acceleration' just below one for 'surface gravity'. They also have the values for Earth, ...
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How to find the mass of a planet not knowing the gravitational constant?
So I found this problem, I know the gravity of earth $g_0$, I found the orbital speed of one satellite using this equation $\frac{GM_em_s}{(R_e+h)^2}=m_sa$
($M_e$ is the mass of earth, $m_s$ is the ...
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Impact on the rest of the solar system if Mercury or Venus were disassembled?
I've watched a few theoretical videos about Dyson spheres where they mention that the most practical way to do that would be to disassemble a planet - preferably one already close to the sun - Mercury ...
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Gravitational waves and gamma ray burst: how were the error bars determined for this speed of gravity calculation? Was $H_0$ used?
This newly updated answer to How precise are the observational measurements for the speed of gravity? and this answer to How is the most accurate value of 𝐺 measured? cites the November 2017 arXiv ...
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If the Sun disappears right now, when the absence of its gravity affects on Earth? [duplicate]
Imagine if the Sun disappears right now. When the Earth will be affected by its absence? Does it affect immediately, or it takes almost 8 minutes? (The time that light travels from the Sun to the ...
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1answer
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Have I nearly found the event horizon of a black hole?
The calculator on the website https://planetcalc.com/1758/ cites Wikipedia's Gravitational acceleration and implements:
$$g = G \frac{M}{(R + h)^2}$$
For a black hole with mass $M$ equal to 5 solar ...
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3answers
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Why are stars still distant from one another? [duplicate]
Why are stars so far from each other? Shouldn't gravity pull them closer over time? And if the effects of gravity are negligible is there an explanation why stars have to be so distant from one ...
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1answer
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Kinetic energy and galaxy arm rotation rate
The higher than expected rotational velocity of stars and gas clouds in the outskirts of galaxies is explained today by invoking dark mater that supplies not only the additional gravitational mass, ...
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0answers
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In space, can you tell that you're flying sideways? [closed]
Imagine a vehicle like the dragon capsule, but the chair is on the bottom and facing forward, and the thrusters are directly behind it as illustrated above. When flying in space towards some planet, ...
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1answer
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Why is the position of the Sun so fixed? [duplicate]
Please correct me if I tell something wrong.
As we already know, a planet (e.g. Earth) remains on its orbit due to the gravity of the Sun.
If the Sun's gravity were not there, the Earth would be ...
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1answer
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Is the gravitational field of the sun uniform?
I understand that rocky bodies in the solar system all exhibit gravitational anomalies. Does the sun exhibit any gravitational anomalies? If so are they distinct enough that it effects the orbit of ...
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1answer
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Can the Earth be used as a gravitational lens?
Could the Earth be used as a gravitational lens to image very far distances with an effective aperture that would be far greater than any telescope? How far away from Earth would an observing ...
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Is light emitted from a heavier body more redshifted than light from a lighter body?
Is light emitted outwards from, say, a region very close to a black hole more shifted than light with the same wavelength that began next to a less massive object?
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How to project an arbitrary elliptical orbit onto the night sky plane?
An ellipse E is arbitrarily oriented in 3-D space with the origin at one of its foci. Use the standard elements provided in the figure. Assume the reference direction $\gamma$ or $\gamma'$ is the ...
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If time is not absolute and depends on the gravitational field, then why we keep using our own (particular) time in cosmology?
Sorry if my question is not really clear, but indeed it is not clear in my mind neither.
But maybe some of you can help.
Time is not absolute and can be affected by the gravitational potential.
Now ...
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Has the permittivity or the permeability of space been measured in a gravitational well?
Technically one might say yes since earth is gravitational well. However I am looking for more data points. For example,
in deep space where voyager might be
at the Lagrange points of massive bodies ...
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1answer
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How strong are the tides raised by Io on Jupiter relative to the ones raised by the Moon on Earth?
There seems to be 2 ways of calculating tidal forces that appear contradictory. Either:
By calculating the difference of Io's gravitational acceleration on a point on Jupiter's near side and the ...
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1answer
142 views
How gravity behaves for an Earth body and for a celestial body? [closed]
Is there any difference in the gravity of the Earth for an Earth body or a celestial body? For example, will gravity be same for an Earth body, compared to the Moon?
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1answer
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What happens when a huge star is being consumed by a black hole
What happens when a huge star in its later stage( iron core) is near a black hole that slowly consumes some of the matter from the star? Would this offset the imbalance caused by iron fusion ...
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2answers
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The anomaly of spiral galaxies and the need for dark matter
Please could some explain this to me - I understand that some galaxies are rotating with a speed that the stars on the outer reaches should not be held within the spiral given the observed matter and ...
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0answers
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Why are pseudo-Newtonian potentials used in studies of accretion processes around black holes?
In accretion processes around black holes, pseudo-Newtonian potentials are defined for the the black hole geometry. For examples, the potentials defined by Paczynski-Wiita and Artemova et al. for ...
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2answers
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In practice, can very high magnetic fields significantly alter the dynamics of an astronomical-scale bodies?
The direct effect of magnetic fields on the dynamics (as in the movements, trajectories etc of the bodies themselves, rather than lower-level phenomena like stellar winds and atmospheric degradation) ...
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Why do planets in red dwarf star systems tend to have a higher probability to get tidally locked?
I have read about about the habitability of red dwarf systems on Wikipedia, as well as some web articles on similar topics. The problem is, it does not explain why and how it happened. Google search ...
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Is it possible make artificial gravitational waves?
Is it possible to generate gravitational waves (creating low or high disturbance in space-time) from very heavy bodies spinning at very high speed artificially?
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1answer
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Does the gravitational attraction near the surface of dense celestial objects diverge from inverse square?
Does the gravitational attraction near the surface of dense celestial objects (neutron star, white dwarf itc) diverge (to infinity) from inverse square?
This question is inspired by the similarity ...
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2answers
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How is the gravitational effect of galaxies outside of the visible universe on galaxies within the visible universe currently modeled?
Given currently accepted models of the universe,
How much mass is outside of the visible universe?
What is the gravitational effect of that mass on the visible universe?
The question How strong is ...
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2answers
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How does energy (from fusion reactions still inside the sun) still have gravitational attraction?
In this answer they say:
While the conversion of mass matter† to energy in the Sun's core now represents a loss of mass proper matter, it turns out that that energy (trapped in the Sun and slowly ...
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1answer
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Impact verses vacuum
How do asteroids, comets and other stuff stay together when colliding in the empty vacuum of space, when they are made up of non-sticky substances like rock?
My understanding is that the force of ...
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2answers
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Largest body in the solar system that a baseball thrown by a professional pitcher could escape
What is the largest (most massive) known body in the solar system that a professional pitcher could throw a baseball off of, i.e. that has an escape velocity lower than ~102 MPH? (45.33 m/s)
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1answer
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Gas Planets composition and gravitational effects
It has been postulated that Gas Giants have a solid core and an obvious gaseous atmosphere. Question: As the gas is a state of matter and gravity draws all matter inward, is the reason the gas is ...
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How does gravity affect a physical clock?
In all the explanations for time dilation and how gravity affects time a common example which is used is "Clock near to the ground will tick away faster than clock away from the ground due to gravity"....
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1answer
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At what gravity does a body's gravitational lensing become observable?
I wonder whether we know at how much gravitation a gravitational lensing around a celestial body becomes observable (visible in the sense of that we see stars on the wrong places, stars behind the ...
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1answer
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Can the gravitational potential in a spiral galaxy be positive?
Thinking about this question I wanted to start with a rough model of the average gravitational potential of the Milky way. I ran across D. P. Cox and G. C. Gomez 2002 Analytical Expressions for Spiral ...
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What influence does the Interplanetary Magnetic Field have on Planetary Orbits?
CONTEXT
The equation $F_D=\frac{GMm}{D^2}$ is a standard equation in Newtonian gravitation. It describes the centripetal force exerted, by a source mass$M$, on a target particle of mass $m$ located ...
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1answer
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How does the surface gravity on Mars vary between the equator and its poles?
A day on Mars is similar in length to the Earth's day. On Earth, due to rotation, the surface gravity varies from 9.78 m/s² (0.997 g) on the equator to 9.832 m/s² (1.003 g) on the poles. I wonder how ...
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1answer
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Gravitational field for oblate spheroid?
Consider a planet, described as an oblate spheroid. Assume that the spheroid is uniformly dense but not a point source. Outside of the object, do all vectors in the gravity field point through a ...
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can gravity be faster than light in some specific cases? [duplicate]
This is a follow up question from
If an event occurs at a point in space time what will an observer experience first, it's gravity or the light from it?
This https://en.wikipedia.org/wiki/...
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If an event occurs at a point in space time what will an observer experience first, it's gravity or the light from it?
Let's assume a person is close enough to an object in space time to be able to observe it's gravitational effects and the light coming from it.
If that object suddenly pops out of existence (...
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2answers
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What observation can be expected on LIGO if any when Betelgeuse goes supernova?
What observation can be expected from the LIGO† gravitational wave observatory if any when Betelgeuse goes supernova?
Could we know that Betelgeuse has gone supernova before we see it light up our ...
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6answers
182 views
Would planet explode without gravity?
A planet (as well as a dwarf planet) must, according to the IAU definition, have sufficient mass to assume hydrostatic equilibrium (a nearly round shape). Does it mean they would break apart or ...
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A question about stress energy tensor at junction surface
I am now reading a paper (whole paper link)which regarding construct a worm hole by cutting off the stress energy tensor and glue interior and exterior space at $r=a$. ‘Nevertheless, I am confused ...
