• S1.E1 ∙ George Takei
• S1.E2 ∙ Christopher Nolan
• S1.E3 ∙ Dan Savage
• S1.E4 ∙ Arianna Huffington
• S1.E5 ∙ Richard Dawkins
• S1.E6 ∙ Jimmy Carter
• S1.E7 ∙ Chris Hadfield
• S1.E8 ∙ Biz Stone
• S1.E9 ∙ Charles Bolden
• S1.E10 ∙ Norman Lear

• S2.E1 ∙ Bill Clinton
• S2.E2 ∙ Larry Wilmore
• S2.E3 ∙ Seth MacFarlane
• S2.E4 ∙ Penn and Teller
• S2.E5 ∙ Susan Sarandon
• S2.E6 ∙ David Byrne
• S2.E7 ∙ Mars 1
• S2.E8 ∙ David Crosby
• S2.E9 ∙ Brian Cox
• S2.E10 ∙ Gina McCarthy

• S3.E1 ∙ Whoopi Goldberg
• S3.E2 ∙ Mayim Bialik
• S3.E3 ∙ Man on Wire
• S3.E4 ∙ Time Travel
• S3.E5 ∙ Theoretical Physics
• S3.E6 ∙ Robert Kirkman and the Walking Dead
• S3.E7 ∙ Jeremy Irons
• S3.E8 ∙ The Martian
• S3.E9 ∙ Ben Stiller
• S3.E10 ∙ Buzz Aldrin
• S3.E11 ∙ Terry Crews
• S3.E12 ∙ Jay Leno
• S3.E13 ∙ William Shatner
• S3.E14 ∙ US Secretary of Defense Ash Carter
• S3.E15 ∙ Hope Solo
• S3.E16 ∙ Search for Aliens
• S3.E17 ∙ The Science of Weather
• S3.E18 ∙ Science of Game of Thrones
• S3.E19 ∙ Herbie Hancock and Wayne Shorter
• S3.E20 ∙ Bill Maher

• S4.E1 ∙ Lance Armstrong
• S4.E2 ∙ Kareem Abdul-Jabbar
• S4.E3 ∙ Jane Goodall
• S4.E4 ∙ Katie Couric
• S4.E5 ∙ Kevin Smith
• S4.E6 ∙ SciFi Meets National Defense
• S4.E7 ∙ Katy Perry
• S4.E8 ∙ Sylvia Earle, Fabien Cousteau & Adrian Grenier
• S4.E9 ∙ James Cameron
• S4.E10 ∙ Celestial Navigation
• S4.E11 ∙ Salman Rushdie
• S4.E12 ∙ Interstellar Space Travel
• S4.E13 ∙ Alan Alda
• S4.E14 ∙ Stephen Colbert
• S4.E15 ∙ True Story of Hidden Figures
• S4.E16 ∙ Sam Harris and the Science of Belief
• S4.E17 ∙ Frank Oz and the Science of Puppeteering
• S4.E18 ∙ Kelly Slater and the Science of Surfing
• S4.E19 ∙ Astronaut Scott Kelly
• S4.E20 ∙ Stephen Hawking

• S5.E1 ∙ Anthony Bourdain
• S5.E2 ∙ Joe Rogan and the Science of Primitive Man
• S5.E3 ∙ The Big Bang Theory's Simon Helberg & Bill Prady
• S5.E4 ∙ US Space Command
• S5.E5 ∙ Vice President Al Gore
• S5.E6 ∙ Actor Jack Black
• S5.E7 ∙ News Anchor Dan Rather
• S5.E8 ∙ Author George R.R. Martin
• S5.E9 ∙ Actress Anna Deavere Smith
• S5.E10 ∙ Actor Jeff Goldblum
• S5.E11 ∙ Actor James Marsden
• S5.E12 ∙ Weird Al Yankovic
• S5.E13 ∙ Author Patricia Cornwell
• S5.E14 ∙ Director Darren Aronofsky
• S5.E15 ∙ Bill Nye
• S5.E16 ∙ Journalist Christiane Amanpour