George B. Rybicki, PhD, is retired researcher at the Harvard Smithonian Center for Astrophysics, USA.

Alan P. Lightman, PhD, is retired researcher at the Harvard Smithonian Center for Astrophysics, USA, and an avid science writer.

Rana Ezzeddine, PhD, is Professor in the Department of Astrophysics at the University of Florida, Gainesville, USA.