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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



NASA/ESA/Z. Levay/R. van der Marel/STScI/ T. Hallas/A. Mellinger

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

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.

 

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