On a clear, dark night in the Northern Hemisphere’s autumn, you can find the Andromeda galaxy without any equipment, a faint smudge of light overhead. It sits about 2.5 million light-years away, which means the light entering your eye tonight left Andromeda around 2.5 million years ago, long before there were any modern humans to [...] The post The Andromeda galaxy is the most distant thing you can see with the naked eye, and the light reaching your eyes from it tonight left some 2.5 million yea