Wearing Ultraviolet Swim Goggles
This is a region of space called the Chandra Deep Field-South, a region of the sky that fascinates astronomers so much that it is one of the best-studied in the whole sky. Over the past few years and into the future, astronomers have been and will be concentrating on this region and one other in the northern sky as part of the GOODS survey, to do the deepest, most sensitive observations they can with every observatory on the ground and in space, in every wavelength possible.
The European Southern Observatory’s Very Large Telescope took its turn, along with the 2.2-eter MPG/ESO telescope. Together they gazed for 55 hours, using the ultraviolet-sensitive VIMOS instrument on VLT and the Wide-field Imager on the MPG/ESO telescope at La Silla.
They announced the result today: a 27-million-pixel-wide image that shows a pool of galaxies, many of them appearing as they were when the universe was only 2 billion years old. These most distant galaxies are a billion times fainter than the unaided eye can see, and not easily visible to optical instruments. Ultraviolet-sensitive instruments like VIMOS (which focused on wavelengths of light in a range between UV and optical), when used in longer exposures, can catch enough of the light from these distant galaxies to reveal them for us to see.
Nearly everything you see in this image (with the exception of a few bright stars in the foreground (part of the Milky Way Galaxy) is a galaxy. Each of those galaxies has billions of stars.
Now, here’s a thought-provoking idea to chew over while you gaze at this picture: the universe looks the same no matter what direction we look in — that is, it has a roughly similar distribution of structure (galaxies and clusters of galaxies) in all directions. This means that if we could point telescopes in all directions of the sky (without interference from the Milky Way) the distant universe would look like this all over the sky. Think about it–countless millions or billions of galaxies… some dating back to the childhood of the cosmos!