Spiral galaxy HUDF-JD2, infrared image. The galaxy is at lower centre. It was found in the Hubble Ultra Deep Field (HUDF), which looks at light from many billions of light years away, dating from the early history of the universe. At this distance, the galaxies are often only visible in infrared. After the Hubble Space Telescope had found it, the Spitzer Space Telescope was used to estimate its size. It was found to be one of the most massive galaxies yet observed in the first few hundred millions years of the universe. It was previously thought that such massive galaxies did not form until later on. This image combines HST and SST data obtained in 2003 and 2004. The result was published in 2005.