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 neighbor—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