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

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10
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5answers
5k views

What is the difference between our time and space time?

I am trying to understand the phenomenon of space-time. But, everything on internet seems to be too complicated for me since I do not have a background in physics. Can anyone give me simple ...
0
votes
0answers
13 views

How small would you have to crush an object for it to become a black hole?

I was wondering how much you had to crush an object for it to become a black hole. Recently I learned that anything could become a black hole (even you) if it were crushed down small enough, for ...
0
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1answer
85 views

Stability of solar system

My question is simple: Is the Solar system stable? You can see this Wikipedia page. Edit: Sorry, because i think my question is more about mathematics and classical mechanics of planets in ...
5
votes
1answer
148 views

How can Halley's Comet be predictable?

How can we know that Halley's Comet is going to come again every 76 years? I understand that the comet has an orbit around the sun but how can scientists know that it won't be thrown off course for ...
1
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3answers
113 views

How does gravity interact with a photon?

If photon is mass-less and gravity can interact only with matter, then how does gravity alter the trajectory of light?
4
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0answers
120 views

Lack of planets in the Oort Cloud

With the current news about the possibility of a planet in the Oort cloud, I was thinking, why is the matter in the Oort cloud distributed so? It makes sense that inside the planet region there is not ...
3
votes
4answers
245 views

What are the arguments against the Feng and Gallo thin disk explanation of galactic rotation curves?

The well-known galaxy rotation problem is described here. Basically (as one moves outward from the galactic centre, $R$ increasing) the observed pattern of variation in orbital speed $V$ is very ...
20
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4answers
7k views

What's the fastest moving object in the universe?

We know that nothing can have proper velocities larger than the speed of light in vacuum. But are there any objects in space that get close to it? Any comets, or other objects thrown by gravity or ...
3
votes
3answers
195 views

Why doesn't the sun pull the moon away from earth?

If the suns gravitational pull is strong enough to hold much larger masses in place (all the planets) and at much greater distances (all planets further away from the sun then earth) why does it not ...
1
vote
1answer
90 views

How can I calculate how the debris of an object ripped apart at the Roche limit will spread out?

Let's say I have a moon orbiting a planet at a distance $d$. Eventually, $d \leq d_R$, where $d_R$ is the Roche limit of the moon-planet system. I can figure out the mass of both bodies by experiment, ...
5
votes
1answer
142 views

Wouldn't the rings of Saturn experience tidal effect?

The "Lord of the Rings" has more than 60 moons, some of which are larger than Mercury. My question is, wouldn't the ring, which is mostly comprised of rocks, experience tidal effect whenever a moon is ...
0
votes
3answers
122 views

“Up” and “down” in Space [closed]

From my understanding, "up" and "down" in space is going towards (down) an object's gravitational pull or (up) which is going away from it. I get confused with this explanation, and I believe simply ...
3
votes
2answers
1k views

What would happen if Jupiter and Earth were at the same distance as the Moon is from Earth?

If Spock came with a super machine capable of moving planets, and placed Earth so close to Jupiter as the Earth's moon, the gravity of Jupiter would make us fall into it?
1
vote
2answers
117 views

On a log-log plot of surface gravity to planet mass, what is the meaning of the y-intercept?

I am playing around with data from exoplanets.org, and am interested in the plot of surface gravity to planet mass. I reproduced this plot after downloading their data and performed a non-linear ...
0
votes
1answer
62 views

Is there a theory / equation showing whether or not two passing bodies will go into orbit around each other?

I am looking for a theory that shows whether or not two passing celestial bodies will go into orbit. I assume there would have to be a critical point where the gravitational attraction is stronger ...
1
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1answer
69 views

Can asteroids contain atmosphere?

Gas is abundance in the universe, can a massive asteroid draws in these gas forming a thin atmosphere?
0
votes
1answer
57 views

Concerning fate of Milky Way Galaxy

Andromeda Galaxy is the largest galaxy in the galaxy cluster[1] called Local Group[2] and our Milky Way Galaxy as well as some satellite/dwarf galaxies are orbiting around each other within Local ...
3
votes
1answer
172 views

Are black holes solely responsible for hyper velocity stars?

I read that the stars orbiting around Sagittarius A* (a.k.a the supermassive black hole located at the heart of the Milky Way) move very fast (many times faster than our Sun moves across the galaxy), ...
-1
votes
1answer
67 views

Why does Earth have more gravitational force than the Moon if I stand on it?

Perhaps this is a silly question but I am trying to understand Einstein's general theory of relativity. I would like to explain my question in more detail. The greater the mass of an object, the ...
3
votes
4answers
730 views

Is Earth's 1g solid surface gravity unusually high for exoplanets?

The surface gravities of the Sun’s planets are all close to 1g, 0.38-2.53 (about a factor of e, by chance). The cloud-top gravity of the gas giants is not too interesting here, but I suppose that the ...
0
votes
0answers
23 views

How much do the mascons on the moon affect surface gravity?

The gravity anomalies on the moon (generally accepted to be caused by mascons) are powerful enough to affect the orbit of satellites. I'm trying to determine how much effect they would have on a ...
1
vote
2answers
166 views

Is it certain that dark matter consists of particles? (And not just curved space)

The main idea about dark matter today seems to be supersymmetry. That there exists a set of yet undiscovered fundamental particles which (in a mathematically most convenient way) mirror the particles ...
4
votes
2answers
386 views

What would happen if a body were to fall into a neutron star?

We know neutron stars as a very massive object with extremely strong gravitational forces that composes mostly of neutrons. I couldn't help but wonder, what would happen if an object fell into a ...
0
votes
1answer
80 views

Collision of asteroid and gaseous planet - what would happen

What happens when asteroids (or other small bodies) "collide" with a gas planet? In my head it would either go through it or just stay "inside" it due to the strong gravity. I tend to believe in the ...
7
votes
1answer
488 views

How much mass does an object in space need to keep a human on its surface?

Assume there were a roughly spherical object in space like a meteorite or a comet. If I weighed 80kg on Earth, how much mass would be required for an object in space so that I could stay on its ...
0
votes
1answer
44 views

Is there a threshold on distance/size for a tidal locking?

I know that some systems tend to tidal locking (such as earth-moon), which occurs basically because the difference in the gravitational pull on one side is significantly different from the pull on the ...
2
votes
1answer
80 views

Gravitational pull needed to keep a gas in atmosphere

How can you determine the gravitational force needed to keep a particular gas in the atmosphere of a planet (for example, carbon dioxide (CO2))? I came across the following formula ...
0
votes
1answer
120 views

Does our sun/solar system orbit around any other celestial objects? [duplicate]

Does our solar system orbit around another massive celestial object? Like a massive star or black hole for instance? From my understanding our sun rotates around the centre of our galaxy, thus our ...
4
votes
2answers
86 views

Does rotation affect gravitational lines of force

I was reading about rotating pulsars and other more-massive objects spinning at absurd speeds (hundreds of revolutions per second), and there was one point of which I was not clear. Does a rotation ...
2
votes
1answer
62 views

How can a galaxy in-between our view and the galaxy behind it have a 'lensing effect'?

In this article, the author writes: This galaxy is so distant that it would have been invisible without the gravitational lensing effects of a large galaxy cluster called Abell 1689, located ...
2
votes
6answers
669 views

Why are stars so far apart?

So, this is mere musing, but it seems that stars are quite extremely far apart. I tried to determine the mean distance between nearest neighbors for stars (in just our galaxy) but I'm not sure what it ...
3
votes
1answer
53 views

Is the SOI a spherical region or a oblate-spheroid-shaped region?

The Wikipedia article on Sphere of influence states that: "A sphere of influence (SOI) in astrodynamics and astronomy is the oblate-spheroid-shaped region around a celestial body where the ...
-3
votes
2answers
104 views

How dense would planet earth have to be to have the same gravity as Jupiter?

I was reading this question about how small could a planet be while having earth-like gravitational pull. This got me thinking, how dense would planet Earth have ...
0
votes
2answers
221 views

Do planets repel?

I know gravity is the result of mass. Gravity is nothing but the attractive force on a body due to its mass. I have a question that may be silly. In magnetism we have attraction and repulsion. Earth ...
2
votes
1answer
112 views

Could a close passing star be captured by the Sun's gravity?

Earlier I read an article here stating that a binary pair of stars passed within 0.8 light years from the sun. That made we wonder why the stars weren't captured by the Sun's gravity since the sun's ...
-3
votes
2answers
110 views

earth is spherical , does it mean the ground on earth is like a ball? [closed]

I know earth is spherical in shape. Does this means earths atmosphere is spherical in shape or the ground/(land+water combined) is in spherical shape. I have some doubts if the second is true. ...
1
vote
2answers
173 views

Why don't we orbit the center of our galaxy?

At the center of the milky way, there must be some giant mass that keeps the galaxy from just floating away from itself. So, obviously, we feel the immense gravitational pull of whatever this is. But, ...
5
votes
2answers
151 views

Tide on the Moon

If the Earth's Moon had a water ocean of depth 2-4 Km, how high would the tides rise due to the Earth's gravity? (Just a hypothetical question.)
4
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6answers
400 views

Why isn't the star that created the black hole a black hole?

If the mass of a black hole is creating so much gravity that light cannot escape, why isn't the mass of the star that created the black hole (before it went supernova) trapping light as well? By all ...
16
votes
2answers
1k views

Do all the objects in the universe exert force on all other objects?

Do all the objects in the universe exert force on all other objects? Like a type of gravity; also, how much does it decrease as it gets farther away?
2
votes
2answers
216 views

If an asteroid twice the size of Earth passed super close would half of the Earth be pulled towards it?

So let's say that an asteroid the twice the size of Earth passed by going relatively slow say in between the Moon and Earth. Among so many other things (and perhaps you can touch on some of the ...
1
vote
1answer
70 views

Question: calculating orbit using another orbit

A satellite which is moving around a planet of mass $M$ in a circular orbit of radius $R$ is given a sudden thrust into the center of the planet, so that it deviates an angle $a$. Find the ...
11
votes
3answers
347 views

Will Saturn's rings become a moon?

Planets form from disks of matter orbiting around a star; some moons form from disks of matter orbiting planets. If this were going to happen around Saturn, approximately how much time would it take?
1
vote
3answers
128 views

Would Pluto keep an orbit without its moon?

I haven't studied space that much, but I know that Pluto has very little gravity, but just enough to keep a human on its surface. Would Pluto keep a regular orbit around the sun without some extra ...
4
votes
1answer
83 views

The role of gravity during planetesimal accretion

As far as I understand, during the formation of a planetary disc, grains of dust stick together due to collisions and chemical bonding. Considering the size of the grain - say, 1 mm - and the speed - ...
1
vote
2answers
146 views

What is the orbit of Earth around the Sun?

According to wikipedia and other sources, a planet and a star always move in a circular orbit around the common center of mass of the both bodies, in case of Earth and sun, this center of mass lies ...
13
votes
4answers
3k views

Is Jupiter made entirely out of gas?

I heard that Jupiter is made out of gas. But in school I learned that Jupiter has gravity which is 2.5 times that of Earth (Gravity that can tear apart a comet) and gravity is proportional to mass. ...
0
votes
2answers
159 views

Why don't small stars end up as a black holes?

I've recently done some research about black holes, and I realized that big stars form black holes and small ones don't. Is it because the gravity isn't strong enough for it to fall in on itself, or ...
3
votes
4answers
270 views

What is the most oblate astronomical object known?

There are some very vast spinning objects out there. How high can the eccentricity get, or, which I think is easier to understand, how small can the ratio between the polar and equatorial diameter ...
1
vote
1answer
54 views

How to convert a gravitational force to speed and direction

I am doing some calculations, and I wanted to know that after using the gravity equation, $$F = G \frac{m_1m_2}{r^2}$$ if you can use $F$ and convert it into a speed, such as km/year, and also a ...