A hoax 'alien invasion' alert in Brazil caused panic and amusement, revealing vulnerabilities in emergency systems. Authorities are investigating the breach.

Imagine receiving an alert on your phone from a government agency at night, warning you about an alien attack, when you have ...

Astrophysicist Neil deGrasse Tyson speaks with CNN’s Dana Bash about "never-before-seen files" on UFOs released by the FBI and the Pentagon last week. "Given the testimonies we have heard delivered in ...

A Ukrainian drone attack on Moscow's oil refinery has triggered a wave of speculation online after videos appeared to show a UFO-like object soaring above the facility.