By Stephen Hawking (University of Cambridge)
By Charles Frankel
By Lliffe, Robert
By Frank Close
By George Musser
By David Baxter
By Ailsa Allaby, Michael Allaby
By A. Meharg
By Mark R. Chartrand, Wil Tirion
By Galileo Galilei, Albert Van Helden
By Hadfield, Chris
By Thomas P. Tomich, Sonja B. Brodt, Randy A. Dahlgren, Kate M. Scow
By Yan Ridpat, Ian Ridpath
By Michael Wall
By J.B. Sidgwick, R.C. Gamble
By Colin Reid
By Govert Schilling, Martin Rees
By J. Kelly Beatty, Andrew Chaikin, Carl Sagan
By Ritchie, Rob
By Tiffany Francis-Baker
By N.A.S.A., Terry Hope