http://www.slate.com/blogs/bad_astr...oup_of_seven_galaxies_at_the_edge_of_the.html
Hubble Sees Tribe of Galaxies at the Dawn of the Universe
By Phil Plait
Posted Wednesday, Dec. 12, 2012, at 3:14 PM ET
An incredibly deep image taken by Hubble Space Telescope has made an amazing discovery: a group of seven galaxies that existed just after the Big Bang itself! One of them may be the most distant galaxy ever seen, a soul-crushing 13.3 billion light years away, and seen as it existed just 380 million years after the Universe itself was born.
The image is a result of 100 hours of Hubble staring at one spot in the sky. They chose the location of the previously-observed Hubble Ultra Deep Field (HUDF), a region of the sky where Hubble had already taken a very long look, taking a census of thousands of galaxies at all different distances. This new observation, though, looked in the infrared, where we expect the most distant galaxies to shine most brightly.
The picture above shows the HUDF. The locations of the seven extremely distant galaxies are indicated by colored diamonds; a close-up of each one is shown on top (click the image to get a high-res version). The number listed with each galaxy is a measure of its distance using its redshift: Because the Universe is expanding, more distant galaxies appear to move away from us faster than nearby ones. That can be used (with some fairly complex physics) to determine the distance to each galaxy. I explain this technique in more detail in an earlier post about redshifts.
The redshift is noted by the letter z, and the bigger the number, the farther the galaxy. A z of 8.6 is a galaxy about 13 billion light years away. The most distant galaxy seen was at a redshift of 11.9, which means the light we see from it left a whopping 13.3+ billion light years ago. Since the Universe is 13.7 billion years old, this means we are seeing this galaxy as it was only about 380 million years after the Big Bang. That's a stunning observation.