Zoom through galaxies to the most distant galaxy yet discovered, UDFy_38125539. The discovery of this galaxy was announced in October 2010. It is thought to be seen at a time when the universe was just 600 million years old, during a period known as the reionisation epoch. At this time, the radiation from the first generation of stars was reionising the fog of neutral hydrogen gas that was permeating the universe. This led to space being filled with low_density ionised hydrogen, transparent to light, as we see today.