Sun and Planets Crashing
Date: 1993 - 1999
Stars generally move in free orbit.
Since the sun is a star why doesn't it crash into planets?
Because the planets orbit the Sun. You might as well ask why the Earth
doesn't crash into the Moon.
The Moon orbits the Earth; the Earth orbits the Sun; the Sun orbits
around the center of the Milky Way; and the Milky Way is moving
through the universe relative to other galaxies. Stars can "crash into"
each other since there are so many of them in our galaxy, and galaxies
can collide, but once a planetary system has formed, it remains stable
unless perturbed by another nearby passing star.
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Update: June 2012