Ancient galaxies revealed by Hubble

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 cosmos was between 1-2,000,000,000 years old.

The HUDF field contains an estimated 10,000 galaxies. In ground-based images, the patch of sky in which the galaxies reside (just one-tenth the diameter of the full moon) largely is empty. Located in the constellation Fornax, the region is below the constellation Orion. The ACS field is studded with a wide range of galaxies of various sizes, shapes, and colors.

In vibrant contrast to the image's rich harvest of classic spiral and elliptical galaxies, there are a myriad of oddball galaxies tittering the field. Some look like toothpicks; others like links on a bracelet. A few appear to be interacting. Their strange shapes are a far cry from the majestic spiral and elliptical galaxies we see today. These strange galaxies chronicle a period when the universe was more chaotic. Order and structure were just beginning to emerge.

COPYRIGHT 2004 Society for the Advancement of Education
COPYRIGHT 2004 Gale Group