Starwatch: the furthest thing you can see with the naked eye

Adjust to the dark and you can peer 2.5m years into the past to see our nearest spiral galaxy, Andromeda

This week, try spotting the furthest thing you can see with the unaided eye. The Andromeda galaxy is a collection of a trillion stars lying 2.5m light years distant. Also known as M31, it is the nearest large galaxy to the Milky Way. Once you have located this admittedly faint object, you can marvel at the fact that the light entering your eye set out on its journey 2.5m years ago - before modern humans evolved.