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The Question

(Submitted March 14, 1997)

What keeps the stars from crashing into each other?

The Answer

There is a very short answer to your question, and that is that space is very large, and there is lots of room for stars, moons, and planets to move around without colliding with each other. Often, when two objects look close together on the sky, one of them is much further away than the other. Therefore, they are not really close together at all. This is true for many of the stars in the constellations that we are familiar with, and it is true for stars and planets which look close to our Moon. The nearest stars are light years away, while the Moon is about a billion times nearer. Collisions between stars are believed to happen, but they must be very infrequent. Collisions inside our solar system happen fairly often between planets and comets or meteors. Each "shooting star" is an example of such a collision, and 2 years ago a fairly large comet collided with Jupiter.

I hope this helps!

Tim Kallman
for the Ask an Astrophysicist team

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