Ancient galaxies revealed by Hubble.

• Position: Astronomy

Astronomers at the Space Telescope Science institute, Baltimore, Md., have unveiled the deepest portrait of the visible universe ever achieved by humankind. Called the Hubble Ultra Deep Field (HUDF), the million-second-long exposure reveals the first galaxies to emerge from the so-called "dark ages." the time shortly after the big bang when the first stars reheated the cold, dark universe.

This historic view is actually two separate images taken by Hubble's Advanced Camera for Surveys (ACS) and the Near Infrared Camera and Multi-Object Spectrometer (NICMOS). Both reveal galaxies that are too faint to be seen by ground-based telescopes, or even in Hubble's previous faraway looks, called the Hubble Deep Fields (HDFs), taken in 1995 and 1998.

"Hubble fakes us to within a stone's throw of the big bang itself," reveals HUDF project leader Massimo Stiavelli. The combination of ACS and NICMOS images will be used to search for galaxies that existed between 400-800,000,000 years after the big bang. A key question for HUDF astronomers is whether the universe appears to be the same at this very early time as it did when the...