This Hubble Space Telescope picture reaches deep into space and time. It shows thousands of galaxies in a tiny patch of sky in the constellation Ursa Major. The most distant objects here are small blue irregular clouds, which lie close to the edge of the observable universe. Their light began its journey through space over 10 billion light years ago, so we see the clouds as they were when the universe was only about a tenth of its present age. The bigger and brighter galaxies in the picture are closer, and so we see them at a much later stage in their evolution. These represent essentially what the universe looks like today. The edge of the observable universe is defined by the travel of light rather than any physical boundary.