Should we take this seriously? The viral videos look like science fiction. But as Nasa appoints a head of UFO research, some say it is time to examine the evidence of alien life.
‘Alien corpses’ presented to Mexican congress
Fact or fiction: Ufologist Jaime Maussan has made alien claims before. Glossary
Ufologist - Somebody who investigates Unidentified Flying Objects.
Nasa - The National Aeronautics and Space Administration, responsible for the US space programme.
Astrophysicist - Scientists who try to understand the contents of the universe.
Cold War - A period of diplomatic conflict between blocs led by the USA and the USSR that lasted from 1947 until 1991, when the USSR collapsed.
Conspiracy theories - Theories that explain world events by blaming shady groups of powerful people operating in secret. Some conspiracy theories have a basis in fact, but many more of them are completely invented. What is more, they often play on dangerous prejudices such as antisemitism. It's worth being especially cautious and critical when you come across accounts that ascribe enormous agency to small and secretive groups.
DNA - Deoxyribonucleic acid is the material in an organism that carries genetic information.