Tonight is Yuri’s Night, celebrating humanity’s first emergence into space with the 1961 flight of Yuri Gagarin.

From YurisNight.net:

“Yuri’s Night events combine space-themed partying with education and outreach. These  events can range from an all-night mix of techno and technology at a NASA Center, to a movie showing and stargazing at your local college, to a gathering of friends at a bar or barbecue.”