The Milky Way is surrounded by older galaxies LYNETTE COOK/SCIENCE PHOTO LIBRARY

Meet the Milky Way’s elderly neighbours. It turns out that the faint galaxies orbiting our own are among the oldest in our universe – a discovery hailed as the equivalent to finding the remains of the first humans that inhabited Earth.

These satellite galaxies, including Ursa Major and Bootes I, are thought to be more than 13 billion years old. The closest is probably Segue-1, some 75,000 light-years away, says Sownak Bose of the Harvard-Smithsonian Centre for Astrophysics.

Most attempts to find older galaxies have looked very …