MARIO LIVIO, Ph.D., is head of the science division at the Space Telescope Science Institute, which conducts the scientific program of the Hubble Space Telescope. He is recognized as a world expert on topics ranging from dramatic explosions like novae, supernovae, and gamma-ray bursts to compact astronomical objects like white dwarfs, neutron stars, and black holes. He has published over 300 scientific papers and has lectured to the public about discoveries in astronomy and cosmology all across the globe.