Host
Neil deGrasse Tyson
Shereen Balles
President Harry S. Truman (voice) / Sherwood Rowland (voice) / (voice)
Seth MacFarlane
Rachel Molly Gruber
Sasha Sagan
Christopher Wren (voice) / Weichelberger (voice)
André Sogliuzzo
Edmund Muskie (voice) / Lab Assistant (voice)
Piotr Michael
William Herschel (voice)
Patrick Stewart
Young Carl Sagan
Elizardo Torrez
(voice) / Birthmark Woman
Trang Vo
Bellaramine (voice)
John Steven Rocha
Angry Scholar #2 (voice)
Paul Telfer
John Herschel (voice)
Jonathan Morgan Heit
Edmond Halley / Robert Hooke (voice)
Cary Elwes
Samuel Pepys (voice)
Tom Konkle
Isaac Newton (voice)
Alexander Siddig
Ibn al-Haytham (voice)
Alfred Molina
Clair Patterson (voice)
Richard Gere
Harrison Brown (voice)
Marc Worden
Cecilia Payne (voice)
Kirsten Dunst
Annie Jump Cannon (voice)
Marlee Matlin
Margaret Harwood (voice)
Peggy Jo Jacobs