Most people understand that the earth moves around the sun and rotates on its axis. However the earth moves more than just around the sun. In fact, our entire actually orbits around the center of the Milky Way at over 500,000 miles per hour. So why don’t we crash into anything? The answer is that everything in our galaxy, and especially in our universe, is really, really, far apart, so it will be a long (billions of years) time before we even come close to something that could hit is. In addition, all the galaxies around the Milky Way are actually moving apart from us. Furthermore, the farther a galaxy is away from us, the faster it is moving away. By solving for the rate of expansion using big telescopes, we can determine the approximate age of the universe by extrapolating the growth rate backward. So we know that the universe is about 14 billion years old! This is super cool!
Spacebook 
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