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Remind me why they don't just fall back to Earth?
it's just weaker
to where satellites are.
I'd fall down.
That's bullshit, Einstein or Shakespeare or whoever said that.
is it really worth spending all that money just to know what the weather's gonna be like?!
we'll find out anyway
it'd be different if they could change the weather
why change it when there are only a few weathers that we could choose from. If we could do a new weather, then that would be good.
down Challenge TV so we can watch early 90s Wheel of Fortune.
some of us have important jobs with massive desks
swinging round over your head but no water falls out trick, but with satellites
In comic book form.
interpreting it through modern dance?
They had a whole exhibition on satellites. It was really interesting and I learnt a lot about satellites and orbits and the like. In fact, I'm probably an expert on the subject now.
If you want an answer to your question, I'd recommend a visit.
i hadn't actually realised he wanted an answer
until I set up a spreadsheet to do the Newtonian calcs.
What I hadn't realised is that orbit isn't a delicate equilibrium. Instead, there is a massive difference between the escape velocity and velocity that would allow the object to crash to earth.
Seeing as you aren't working against gravity to increase angular velocity, it doesn't take much energy to correct for loss of velocity through atmospheric resistance etc., hence why satellites only need small thrusters to maintain orbit.
The moon still intrigues me though, as it has no means of correction, aside from interactions with other planets and the sun. Perhaps this is enough to keep it stable, but it seems lucky that it has worked out this way. Perhaps a physicist will explain.
But that said its orbit is decaying. It will just take you quite a long time to notice it.
that the moon has the exact velocity to keep it in orbit for millions(?) of years? Isn't it much more likely that it would have escaped or come down than it would be in orbit over such a long period?
An early 'whoa' moment is when you realise that the orbit of the moon and the rotation of the moon is the same, due to tidal lock: http://en.wikipedia.org/wiki/Synchronous_rotation and then the point at which I completely lose track of what's going on is when precession starts to get factored in: http://en.wikipedia.org/wiki/Orbit_of_the_Moon
The velocity (ie its speed and direction) determines the shape and size of the orbit. You mentioned escape velocity, but in fact escape velocity is what's required to avoid falling into any orbit. From the surface of the Earth that's about 11km/s. If you fire a rocket straight up that fast then it will never return. If you fire it more slowly straight up it will fall back to Earth or enter an orbit if you fire it up at an angle (loosely speaking).
The reason lots of objects fall into orbits relates to the stability of the equations of motion. An orbit is a stable state, as is "fallen back to the ground". Objects will eventually tend towards one of these stable states, and then stay there, hence why the moon has been orbiting the Earth for so long.
marckee's point about precession is also a stability-related phenomenon. Although celestial objects (including the Earth) "wobble" about their axes and orbits, the forces acting on them always pull them back towards the same stable state, so you end up with complicated patterns of movement that still the same always remain within the same broad trajectories.
Oi'm not luckin' for a new ingland
Am just lucking for another gurl