Great Heroes and Discoveries of Astronomy

The landmark accomplishments of Edwin Hubble, Albert Einstein and Carl Sagan; some of the fascinating astronomical discoveries tied to their legacies; the many other great heroes of astronomy who help make these scientific strides possible.

Henrietta Swan Leavitt makes sense of Cepheid variables; she calculates the relationship between their periods and their true luminosities; Edwin Hubble uses Leavitt's work to measure the distance to the Great Andromeda Nebula in the 1920s.

The mysteries of Hubble's law; looking at each part of this deceptively simple equation; the many heroes behind the law; Vesto Slipher, an astronomer at Arizona's Lowell Observatory; Georges Lemaitre, who may have influenced Hubble's insights.

The story of Edwin Hubble's famous namesake; the Hubble Space Telescope; the heroes who help make this vision a reality; the astrophysicist Lyman Spitzer; Nancy Roman; a team of astronomers who help repair a critical problem post-launch.