“The near side of a galaxy is tens of thousands of light-years closer to us than the far side; thus we see the front as it was tens of thousands of years before the back. But typical events in galactic dynamics occupy tens of millions of years, so the error in thinking of an image of a galaxy as frozen in one moment of time is small.”

American astronomer, planetary scientist and science communicator

Carl Edward Sagan was an American astronomer, planetary scientist and science communicator. He worked at Harvard as an assistant professor before moving to Cornell University, where he became the David Duncan Professor of Astronomy and Space Sciences and directed the Laboratory for Planetary Studies. Sagan took an active role in the Mariner, Viking and Voyager programs. He also wrote more than 600 scientific papers and articles, along with several popular science books, beginning with The Cosmic Connection. His The Dragons of Eden won the Pulitzer Prize for General Nonfiction.