• 
  Phil Plait

   Self - Astronomer
• 
  Michelle Thaller

   Self - Astronomer
• 
  Eric Loren

   Narrator (6 episodes, 2014)
• 
  Hakeem Oluseyi

   Himself, Astrophysicist (3 episodes, 2014)
• 
  Grant Tremblay

  Self - Astrophysicist
• 
  Andres Williams

  Self - Narrator
• 
  Mark Sykes

  Self - Planetary Scientist
• 
  Richard Cotton

  Narrator

• 
  Laura Danly

  Self - Astronomer
• 
  S. James Gates

  Self - Theoretical Physicist
• 
  Chat Hull

  Self - Astronomer
• 
  Jess Johnson

  Self - Astronomer
• 
  Timothy Linn

  Self - Chief Systems Engineer Lockheed Martin Space Systems
• 
  Michael J. Massimino

  Self - Astronaut
• 
  Bashar Rizk

  Self - Planetary Scientist

• 
  Peter Schultz

  Self - Planetary Scientist
• 
  Massamiliano Vasile

  Self - Aerospace Engineer
• 
  Rex Walheim

  Self - Astronaut
• 
  Pat Whipps

  Self - Resident Manager NASA Michoud Assembly Facility