An Ancient Universe: How Astronomers Know the Vast Scale of Cosmic Time


Hubble Deep Field

In December 1995, the Hubble Space Telescope, high above the Earth, focused on a tiny spot of dark sky for over 150 consecutive orbits. The result was the deepest view into space we had ever had up to that time. Here we see about a fourth of that "deep field" and it shows galaxies (and only galaxies) at many different distances. The farthest among these galaxies is estimated to be so far away, its light has taken over 10 billion years to reach us. So we are seeing these galaxies as they were billions of years ago, when they were much younger. (Courtesy Robert Williams, the Hubble Deep Field Team, and NASA)

Return to An Ancient Universe
The Age of Light From the Most Distant Galaxies