It Begins Here at Home, Part II

One of the things I absolutely love about astronomy is that it’s just outside the door. You go out, you look up and you see things. During the day you know the Sun’s there, and part of the month you can also see the Moon.  At night, the stars are there for your exploration, along with the planets, and an amazing array of deep-sky objects such as nebulae.  What if you had such concentrated and perfect eyesight that you could look across more than thirteen billion light-years of space to some of the earliest galaxies and galaxy “seedlings” ever formed?  Well, people right here on Earth can do that. They’re using a magnificent time machine called the Hubble Space Telescope to do it.

Over a period of ten years, astronomers have aimed the telescope at a patch of sky in the constellation Fornax and taken images of distant galaxies in that direction. They’ve essentially used HST as a big light bucket for a decade to collect faint light streaming from thousands of galaxies.

The resulting image is called the Hubble eXtreme Deep Field (XDF), and it has gorgeous spiral galaxies similar in shape to our Milky Way and the neighboring Andromeda Galaxy.  There are also large, old fuzzy red galaxies where the formation of new stars has shut down.

If you look closely at the large version of this image, you’ll find tiny, faint, and extremely distant galaxies sprinkled across the image. Think of these as the “seedlings” from which today’s  striking galaxies grew.

This whole image is basically a history of galaxy formation — from the first shreds of galaxies to the enormous and grand galaxies we see today in near-Milky Way space.
Hubble used two instruments to get this image. It took the Advanced Camera for Surveys and the Wide Field Camera 3 to get this level of detail from 2,000 images taken over a total exposure time of 2 million seconds spread out over ten years.  Why take so long?  The longer you look, the deeper you look, and the deeper you look, the further back in time you see. Thus, Hubble is really a time machine, showing us the distant universe — all the while orbiting Earth and sending back data and images to astronomers right here on the planet.  It’s really pretty amazing when you think about it.

To learn more about this image, surf on over to the Hubble Space Telescope Web site, and feast your eyes on bigger versions of this image. It’s worth exploring!