Gravity.

originally posted by: Out6of9Balance
a reply to: Soylent Green Is People

But satellites don't have gravity of their own.

That's irrelevant. The satellites are like the cannonballs in Newton's thought experiment. It's the gravity of the Earth pulling on the satellite that keeps the satellite in orbit -- not the gravity of the satellite (or the cannonballs).


[by the way, satellites and cannonballs and everything else with mass (such as you and me) exerts their own gravitaional pull. However, the gravitational pull of a satellite is miniscule compared to the Earth it orbits, so that gravitational pull of the satellite could be ignored]

a reply to: Soylent Green Is People

Then why are meteors that pass earth pulled towards the earth?

originally posted by: Out6of9Balance
Then why are meteors that pass earth pulled towards the earth?

Gravity.

a reply to: peck420

I assume meteors go faster than satellites yet satellites stay in orbit and meteors strike earth.

And yet the stationary satellites don't come down.

originally posted by: Out6of9Balance
a reply to: Soylent Green Is People

Then why are meteors that pass earth pulled towards the earth?

Maybe for some. But most shooting star meteors you see are due to the Earth moving through dust as the Earth circle the Sun.

That is to say, the Earth moving around the Sun moves at about 60,000+ mph relative to the dust or dust cloud, then runs head-on into that dust, with that collsion creating the meteor.

originally posted by: Out6of9Balance
a reply to: peck420

I assume meteors go faster than satellites yet satellites stay in orbit and meteors strike earth.

And yet the stationary satellites don't come down.

Directions of forces have critical impacts on the overall actions of a given body.

originally posted by: Out6of9Balance
a reply to: peck420

I assume meteors go faster than satellites yet satellites stay in orbit and meteors strike earth.

And yet the stationary satellites don't come down.

I'm discussing this since:

originally posted by: Soylent Green Is People

originally posted by: Out6of9Balance
a reply to: oldcarpy

Not if could jump a few hundred miles.

Or is my knowledge of modern science wrong again?

Science doesn't say that. Science says if you jumped up a few hundred miles (heck -- let's say a few thousand miles), gravity would pull you back down to the ground with a splat.

a reply to: peck420

If you claim that stationary satellites don't come down because they are too far from earth for earth's gravitational pull to have effect then what Soylent Green is People posted is wrong.

originally posted by: Out6of9Balance
a reply to: peck420

If you claim that stationary satellites don't come down because they are too far from earth for earth's gravitational pull to have effect then what Soylent Green is People posted is wrong.

You would have to be illiterate to take that from my post.

a reply to: peck420

Just saying.

Come on everybody, this is a troll. Nobody could argue this badly while reading a thread full of information unless willlingly.

Out6of9Balance ignores the explanations of Newtons laws, returns to "floating" (urgh) every other posting and is overall on the level of a 5th or even 4th grader it seems. This is not a congruent image that person has built and therefore I think this is nothing but timewasting trolling.

I'm out. Out6of9Balance, if you are truely in search of answers, read about newtons laws. And vectors. And general physic formulas. And a lot of everything else.

originally posted by: Out6of9Balance
a reply to: peck420

I assume meteors go faster than satellites yet satellites stay in orbit and meteors strike earth.

And yet the stationary satellites don't come down.

I explained the stationary satellites in a post above. Even the geostationary satellites move around the Earth. However, that movement matches the rotation of the Earth, so as the Earth rotates, so does the geostationary satellite move in order to match that rotation.

Therefore, the geostationary satellite always appears in the same spot above a point on the Earth's surface, even though the satellite is really orbiting.



en.wikipedia.org...

a reply to: ManFromEurope

Bye bye!

a reply to: Soylent Green Is People

That doesn't explain why gravity doesn't pull them down.

You said if I jumped thousands of miles high I would come back down.

originally posted by: Out6of9Balance
Just saying.

Just saying what? That basic concepts elude you?

I am fairly certain everyone here already knows that.

a reply to: peck420

bummer

originally posted by: Out6of9Balance
a reply to: Soylent Green Is People

That doesn't explain why gravity doesn't pull them down.

You said if I jumped thousands of miles high I would come back down.

As explained several times above, the sideways momentum (motion parallel to the earth's surface) keeps them from hitting the ground, like the Newton's cannon thought experiment I posted. Cannonball A and B were not moving fast enough, so Earth pulled them to the ground. Cannonball C was moving fast enough that as Earth pulled back, the cannonballs speed allowed it to miss the part of the Earth that curved under itself.

So cannonball C perpetually falls toward Earth in a sideways direction that allows it to perpetually miss the ground.

A stable orbit is created when the orbiting object has enough "sideways" momentum to balance out the pull of gravity. It's balanced so neither wins: the satellite does not move so fast sideways as to zoom off into space, nor does the Earth pull so hard relative to that satellites' motion as to pull it back. A balance.

That's why the Space station moves at 17,000+ mph around the earth. At the space station's altitude of about 200 miles, it needs to move sideways at about 17,000 mph so it misses the earth as Earth pulls back on it.

a reply to: Soylent Green Is People

Astrosociety.org claims at the equator the earth spins at 1000 miles/hour.

So let's say I take a 5000 miles jump there, upwards ofcourse, let's say it takes one minute to reach my highest point, that would mean I'm in non-stationary orbit, since the earth spins.

You said I would come back down.

Satellites don't come down.

Can you explain?

originally posted by: Out6of9Balance
a reply to: Soylent Green Is People

Astrosociety.org claims at the equator the earth spins at 1000 miles/hour.

So let's say I take a 5000 miles jump there, upwards ofcourse, let's say it takes one minute to reach my highest point, that would mean I'm in non-stationary orbit, since the earth spins.

You said I would come back down.

Satellites don't come down.

Can you explain?

Before you jumped, you had a 1000 mph motion that the earth imparted on you because you were standing on that Earth.

As you jump up 5000 miles, you would retain that 1000 mph sideways speed because there would be no force slowing you down (objects in motion tend to stay in motion unless acted upon by another force). So you could hypothetically be moving at 1000 mph, but that's not fast enough for an orbit.


Let's look at the example of a geostationary satellite. Geostationary satellites orbit at about 22,500 miles up. As I mentioned in another post, they move at a speed that keeps them above the same point on Earth as the Earth turns. But even though the Earth turns with a speed of 1000 mph at its surface, that's not the speed a satellite at 22,500 miles up must move to keep up with the turning Earth; the geostationary satellite needs to move much faster.

That's because at 22,500 miles up (a radius of 26500 miles to the center point of its orbit), the circumference of the satellite's orbit is roughly 165,000 miles. Compare that to the circumference of the Earth, which is roughly 25,000 miles. So while the Earth turns 25,000 miles in one day (which is roughly 1000 mph at the surface), for a geotationary satellite to keep up (remain above the same point of a rotating Earth), it needs to cover 165,000 miles in one day, or about 6900 mph.

So even if you jumped 22,500 miles straight up, while you'd be moving sideways at 1000 MPH you would instead need to be moving sideways at 6900 mph to achieve an orbit (to "miss the ground" as Earth pulls you back, as decribed before). Otherwise you will not miss the ground as Earth pulls you back.


And the 22,500 mile altitude/6900 mph angular momentum (sideways speed) is special just for geostationary satellites. Low Earth orbit is different and not geostationary. The space station (ISS) is at low earth orbit of about 200 miles, and circles the earth in about 90 minutes, which equates to about 17,000 mph. That 17,000 mph angular speed is necessary becuase it is so close to the earth that it must go faster to make sure it gets to the point where Earth "gets out of the way" by curving under itself (as described in other posts above).


Edit to add:
See my post below if you want to know what you need to do to float away from Earth.

If you jumped up with a straight-up speed of about 26,000 mph, you would escape earth's gravity and float around in an orbit around the Sun.