This weekend, more than 20 years after his last extraterrestrial-focused feature, Steven Spielberg returns to his roots with Disclosure Day. The movie draws from the filmmaker's career-spanning fascination with the possibility that life exists somewhere other than Earth.

Scientists and public health advocates are urging for preparedness in advance of confirmation of the discovery of extraterrestrial life.

Here's a rundown of 21 celebrities who believe aliens are real, and what they've said about our extraterrestrial neighbors. "It’s my first film that will be considered science fiction that I do not consider to be science fiction,