Re: Why doesn't the suns gravity pull earth in.

Dear Gilbert,
     The sun's gravity IS pulling us in! Ever since the solar system 
condensed from a vast cloud of dust and gas some 5 billion years ago the 
earth has been falling. However, fortunately for us, we are also zooming 
sideways at an average of 67,000 miles per hour, so by the time the sun 
pulls us down, we have sailed over its horizon. 
     Here's how Isaac Newton explained it 300 years ago. Suppose you throw 
a ball. It sails a ways and gravity pulls it down. Throw it very, very 
hard. It sails much further before gravity pulls it down. Now mount your 
ball on the nose of the mighty Atlantis Space Shuttle and kick it up to 
some 18,000 miles an hour. It is moving so fast that it sails beyond the 
horizon before it falls to earth and we say it is in orbit.
     In the same way our earth is orbiting around the sun. If you could 
accelerate yourself to 67,000 miles per hour some distance ahead of or 
behind our sun, yes, you would be in orbit and wouldn't need your 
thrusters (until it was time to come home!).
Jim Foerch
Veen Observatory
Lowell, Michigan, USA