Hey neighbor, it's World Space Week!

Space is a big, lonely place, so it's nice to know we have neighbors. The pictured Andromeda Galaxy is our Milky Way's closest—right next door at 2.5 million light years away. Our cordial relationship with Andromeda goes back about 10 billion years to when both galaxies were still forming. But trouble is brewing: Andromeda is on a collision course with the Milky Way, due for impact in 4 billion years. This neighborhood's about to get rough…
© NASA/JPL-Caltech