Sunday, October 21, 2012

Extremely Deep View of the Universe

Last month, the Hubble Space Telescope released one of the most impressive astronomical images ever taken and I wanted to share it with you. Called the Hubble Extremely Deep Field, it shows a tiny, tiny portion of the sky in the constellation of Fornax -- a portion about the same size (angle) in our sky as one of the smaller dark splotches (maria) you can see on the Moon.

Between 2002 and 2012, a team of astronomers kept photographing this same bit of sky over and over again for 2 million seconds (almost 23 days) and the results, as you can see, are spectacular. Almost every bit of light you see on the accompanying picture is a galaxy (a collection of millions and, more likely, billions of stars). Some are so far away, light from them is estimated to take 13 billion YEARS to reach us!

This means that when you look at the faintest objects in this picture you are looking almost back to the beginning of time (the Big Bang is estimated to have taken place 13.7 billions years ago.) Some 5,500 galaxies are visible in the small frame of this image and they range in distance and time over billions of lightyears and years. In such images, which are like core samples in geology, astronomers can study the history of structure and matter in the universe.

The Hubble scientists have done this before, taking previous sets of deep images called the Hubble Deep Field and then the Hubble Ultra-deep Field.  But the current image (above) shows by far the deepest view (seeing the faintest galaxies and light from longest ago.)