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

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7
votes
2answers
336 views

What was the length of year 1 million years back?

We know that the universe is gradually expanding and this indirectly means that the gravitational force between sun, earth, planets and other stars (roughly anything in the universe) is gradually ...
3
votes
4answers
245 views

If the hammer and feather move at the same speed why do comet and the tail particles move at different speeds?

From this exhibition by an astronaut on the moon dropping a hammer and a feather and showing they move at the same speed, why do the particles of the comets tail move away from the comet, slow down ...
4
votes
1answer
66 views

What's the smallest scale at which dark matter has been measured?

What is the smallest scale at which we have detected "dark matter" (more kinetic energy than would be predicted)? If you don't mind indulging a follow-up: Would its detection on smaller scales be ...
5
votes
1answer
74 views

Are there any alternative explanations for the gravitational force we attribute to dark matter?

It always seemed counter-intuitive to me that we observed an measured a gravitational force and since the universe has not enough mass to account for it, the conclusion was to say there's a different ...
12
votes
4answers
346 views

Doesn't gravity attract objects in space until they collide?

If the formula to calculate the force of gravity of two objects is: $$F1 = F2 = G * (M1 * M2/r^2)$$ Why do planets stay in orbit? Or is there another formula at work?
12
votes
3answers
241 views

Does a planet's mass or gravity affect the height of it's mountains?

According to this Wikipedia page, the top five highest mountains on Mars (and the highest on Venus) are all taller than Mount Everest (and Mauna Kea as measured from the ocean floor). Does a planet's ...
15
votes
3answers
2k 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 ...
6
votes
0answers
103 views

Determining effect of small variable force on planetary perihelion precession

Is there an analytical technique for determining the effect of a small variable transverse acceleration upon the rate of precession of a planet orbitting around the Sun according to Newtonian gravity ...
8
votes
5answers
164 views

Orbiting around a black hole

Is it possible (for either a satellite or a planet) to orbit around a black hole? Do they attract everything around themselves into the center? Or they just affect gravitational force just like stars? ...
8
votes
1answer
110 views

Parking a telescope at a Lagrange point: is this a good idea from a debris point of view?

The James Webb space telescope is supposed to be located at the Earth-Sun L2 Lagrange point. Do we expect the region around that point to have a higher concentration of space debris, asteroids, ...
9
votes
1answer
545 views

Is the moon moving further away from Earth and closer to the Sun? Why?

According to The NASA Moon Facts page: The moon is actually moving away from earth at a rate of 1.5 inches per year. Why is the moon moving further away from the Earth? Is this a result of the ...
12
votes
4answers
129 views

What is Gravitational Lensing?

What is the effect known as gravitational lensing? How does it work? What objects would be able to cause this effect?
11
votes
3answers
356 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?