Are the planet falling?

FOS5252

Hi,

I have been thinking about this question for awhile now and I would really love if someone could answer it.

I understand why we fall to the earth and I also understand how orbit of the international space station occurs due to the fact they are falling at the speed of gravity horizontally but I am curious if the planets and galaxies themselves are falling through space?

And if all the objects in the universe are falling due to gravity, is the universe itself falling due to gravity?

If someone could shed some light onto this so I can finally get some sleep

Morbert

FOS5252 wrote: »

Hi,

I have been thinking about this question for awhile now and I would really love if someone could answer it.

I understand why we fall to the earth and I also understand how orbit of the international space station occurs due to the fact they are falling at the speed of gravity horizontally but I am curious if the planets and galaxies themselves are falling through space?

And if all the objects in the universe are falling due to gravity, is the universe itself falling due to gravity?

If someone could shed some light onto this so I can finally get some sleep

Yes, they are falling, provided we are clear with what we mean by falling. Falling, in this context, means "following a straight line through spacetime".

More intuitively, (and less helpfully in this context) we say we are falling if we don't experience any external forces. Hold your hands out and you will feel gravity pulling on them. Jump up in the air, and for the small time that you are falling, your arms will feel weightless.

FOS5252

I mean falling in the same sense that an apple falls to the ground, a planet will "fall" through the universe. Planets are falling in orbit around one another so intuitively it would seem they must also be dropping in a downward direction as well?

rocoso

shouldn't worry about it by the time the universe decides to reverse we will all be long gone including our planet earth.....space station is kept in orbit because of the fact that the forces of its mass trying to exit earths gravity are equal to the gravitational pull of earth....but not quiet off course the forces generated to put any satellite into orbit decay over time and so they eventually come back to earths atmosphere and crash and burn on the way in due to friction....
our universe is still in expansion and is expanding at an exponenitial rate...

BrianG23

FOS5252 wrote: »

I mean falling in the same sense that an apple falls to the ground, a planet will "fall" through the universe. Planets are falling in orbit around one another so intuitively it would seem they must also be dropping in a downward direction as well?

This question is so confusing for me...

Morbert

FOS5252 wrote: »

I mean falling in the same sense that an apple falls to the ground, a planet will "fall" through the universe. Planets are falling in orbit around one another so intuitively it would seem they must also be dropping in a downward direction as well?

If by falling you mean dropping in a downward direction (I.e. Towards the sun) then the planets aren't falling (at least not yet).

http://www.theregister.co.uk/2008/02/27/sun_swallow_earth/

rocoso

it is a confusing question indeed I think FOS5252 you may be confused about gravitational pull as regards the equilibrium of space objects

BrianG23

All I get is

Moon orbits planet, planet orbits star, star orbits galaxy, galaxy moves away from center of verse. That's generally how it is although it can get more complicated when Planets are bigger than their star, Black holes, or two stars are orbiting each other. But generally all of these things will also be orbiting around the galaxy

Orbiting is falling in two directions and coming to a direction in the middle Fos. You have vertical(falling towards earth/gravity) and horizontal(momentum/falling at ...long explanation). If the vertical is too strong, the orbiting object will collide with the planet. If it's too weak to counter the horizontal momentum...it will break orbit and fly away. If neither is strong enough you will have an orbit, provided the object isn't pointed at the planet in the first place. Humans, and everything stuck on earth...have little to no V in the diagram.


Orbit does not have to be a circle either. It can be a really strung out oval. Their are Asteroids orbiting the Sun that go so far away from it and then come closer than Mercury to it.

There is not falling through the universe either. There is something pushing the Galaxy away from a point, we don't know what it is. But the Galaxy itself, with all it stars and ****, is sorta by itself maintaining itself. There is nothing else exerting force on it(besides abysmal gravity from other galaxies and again, that force pushing us away from the center)

If i'm wrong someone correct me. If i'm right and you don't understand Fas...just look up a few things if you really want to understand it. Some people just don't get it though...my mother cannot understand how the Earth is round and how we don't fall off...the poor women.

FOS5252

Sorry I was quite tired when I wrote this and probably and I do not come from a physics or science degree so I am probably making huge assumptions.

My question is are the planets and solar systems static in the universe? I have heard that solar systems do collide (trust me I am not worried about it) but I want to know are they in laymans terms simply only going left or right in direction( as marbles do when they are on the floor)?

Or are they with going left and right also going up and down in direction? (A case of throwing two marbles off the empire state building at each other) where they are both falling and going in a sideways direction?

I know that gravity is the same force we experience here as in space so if I drop something from the top of a building it will fall towards the earth. I want to know is earth also falling through a ever expanding universe trying to hit the bottom?

28064212

"up" and "bottom" don't have any real meaning when you're talking about the universe. You can only describe movement relative to something else. In your marble example, the marble falls downward at a speed (accelerating at 9.8m/s2). But speed and direction are relative to the ground. That marble is also travelling at around 1,000 miles per hour in a circle around the center of the planet. And the marble is travelling at around 67,000 miles per hour relative to the sun.

So when you talk about upwards or downwards movement, you have to define what up is relative to. Is it the center of the universe? In which case yes, all the galaxies are moving in all three dimensions relative to that point

FOS5252

28064212 wrote: »

"up" and "bottom" don't have any real meaning when you're talking about the universe. You can only describe movement relative to something else. In your marble example, the marble falls downward at a speed (accelerating at 9.8m/s2). But speed and direction are relative to the ground. That marble is also travelling at around 1,000 miles per hour in a circle around the center of the planet. And the marble is travelling at around 67,000 miles per hour relative to the sun.

So when you talk about upwards or downwards movement, you have to define what up is relative to. Is it the center of the universe? In which case yes, all the galaxies are moving in all three dimensions relative to that point

Beautiful, thank you