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If the Universe Is Expanding, Why Are the Milky Way and Andromeda Galaxies on a Collision Course? [Video]

Caleb Scharf, director of astrobiology at Columbia University, answers questions submitted to our YouTube Spacelab Channel

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Questions answered in this episode:

" If you were standing near the event horizon of a black hole and someone pointed a beam of gamma rays at you, would they remain gamma rays or turn into something else?" - ciaran mccormick "If the universe is expanding, and galaxies are moving farther apart, then why is it that the Milky way and Andromeda galaxies are on a collision course?" —theinsanity3 "Why do the planets, asteroids (in general) and our solar system orbit the sun in a flat orbit with all the planets in the same plane ?" —yassine Laarichi


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Submit your questions for the next round of Ask the Experts by clicking here and posting in the YouTube comments (Google account required). And while you're there be sure to subscribe to our Spacelab channel for weekly videos on space and astronomy. 

The question with the most "likes" will be answered in the next video by a new guest expert. Previous episodes have featured astrophysicist Neil deGrasse Tyson and Scientific American's own editor in chief, Mariette DiChristina.

 

About Eric R. Olson

Eric is multimedia journalist and producer who specializes in science and natural history. His work has appeared on the websites of Scientific American, Nature, Nature Medicine, Popular Science, Slate and The New York Times among many others. He is a former video producer & editor for Scientific American.

More by Eric R. Olson

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