In 1995, astronomers pointed the Hubble space telescope at an apparently blank piece of sky for 10 days, and came up with the famous Hubble Deep Field image — showing thousands of galaxies in a patch of sky no bigger than a grain of sand held at arm’s length. After a servicing mission upgraded Hubble’s instruments some more, a 28 day image was taken of another “empty” piece of sky, this one near the constellation Orion. With new instruments, this yielded the Ultra Deep Field image, showing even more galaxies in fantastic detail.
The attached video from Tony Darnell of DeepAstronomy.com gives you a little history of both images, and includes a fly-through of the Ultra Deep Field image, with depth rendered from the red-shift distances of all 10,000 galaxies that it contains.
Make sure you check out Tony’s YouTube channel for more good astronomy-related videos, and while you’re at it, here’s the original video press release on the Ultra Deep Field: