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 - just 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 four billion years. There goes the neighbourhood.
© NASA/JPL-Caltech