• 
  Rene Breton

  Himself - Astronomer
• 
  James S. Bullock

  Himself - Astrophysicist (as James Bullock)
• 
  Ian Chapman

  Himself - Physicist
• 
  Laura Danly

  Herself - Astronomer
• 
  Alex Filippenko

  Himself - Astrophysicist
• 
  David Kipping

  Himself - Astronomer
• 
  Andrea Molinario

  Himself - Physicist
• 
  Elizabeth Newton

  Herself - Astronomer (as Elisabeth Newton)

• 
  David O'Brien

  Narrator
• 
  Hakeem Oluseyi

  Himself - Astrophysicist
• 
  Phil Plait

  Himself - Astronomer
• 
  Mike Rowe

  Narrator
• 
  Caleb Scharf

  Himself - Astronomer
• 
  Dan Stark

  Himself - Astrophysicist
• 
  Michelle Thaller

  Herself - Astronomer