The Deep Field Image

The image shown here is the third of Hubble’s Deep Field images, called the Ultra Deep Field.  It is a composite of 800 separate exposures, requiring a total of 11.3 days of observing time.  Although it reveals about 10,000 galaxies, the area of sky covered by this image is very small.  It would take 50 of these images to cover an area of sky the size of the moon.  To image the entire sky to  this level with existing equipment would require 1 million years of continuous viewing.

 

The galaxies shown here are very faint and very distant.  They are probably the first galaxies formed after the early universe cooled enough to form stars, and then clustered into galaxies.