Overview:All good travel guides need a map, and the team unveil the most detailed 3D map of the Milky Way ever produced. A map that reveals that there may be 50 per cent more stars in the galaxy than we previously thought. American astronomer Neil deGrasse Tyson gives us a guided tour of the strangest stars we have ever observed, and we discover that the Milky Way may already be colliding with our neighbouring galaxy, Andromeda.