Hey neighbour, it's World Space Week!

Space is a big, lonely place, so it's nice to know we have neighbours. 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 the trouble is brewing – Andromeda is on a collision course with the Milky Way, due for impact in 4 billion years. This neighbourhood's about to get rough…
© NASA/JPL-Caltech