An international team of astronomers has detected one of the earliest clusters of galaxies ever identified, located about 12.5 billion light years from Earth. Because light from such distant objects takes so long to reach earth, our telescopes act as time machines, catching this cluster in the act of formation when the universe was only 1 billion years old.
Astronomer Grant Wilson says, "Clusters, which are some of the biggest structures in the universe, are relatively rare. If galaxies spread through the universe are like towns dotting the Earth, fully grown clusters would be like the biggest cities." He compares this discovery to peering at the first houses on Manhattan Island, destined to be among the most populous places on the planet. Astronomers are essentially looking back in time at the early days of an object which someday will be one of the most massive in the universe.