The finite time required for light to travel from a distant galaxy means that we see the universe as it was when the light left each source; thus, more distant galaxies are seen at earlier times in the history of the universe.
The increased sensitivity of astronomical observatories now allows the detection of galaxies in their youth, only a few billion years after the Big Bang and several billion years before the Earth formed. The galaxies contain hundreds of millions of stars spread over distances of 100,000 light years.
In the Department of Astronomy at UW-Madison, we are engaged in the exciting exploration of the universe throughout cosmic time. We make observations in many wavelength bands in order to maximize the available information about distant and extremely faint galaxies.