Join or Sign In
Sign in to customize your TV listings
By joining TV Guide, you agree to our Terms of Use and acknowledge the data practices in our Privacy Policy.
A documentary spotlighting scientists who are studying possible alien life.
There are no TV Airings of The Definitive Guide to Aliens in the next 14 days.
Add The Definitive Guide to Aliens to your Watchlist to find out when it's coming back.
Check if it is available to stream online via "Where to Watch".