Self - Astrophysicist/Author (8 episodes)

Self - Astrophysicist/Author (5 episodes)

Self - Astrophysicist/Author (6 episodes)

Self - Physicist (1 episode)

Self - Astrophysicist/Author (22 episodes)

Himself (1 episode)

Self - Astrophysicist (2 episodes)

Himself - Panelist (1 episode)

Himself - Scientist (10 episodes)

Self (6 episodes)

Self - Astrophysicist (8 episodes)