By Kevin Buhl Jakobsen · New questions every night
🔬 Who came up with the theory of relativity?
💡 Einstein's special relativity came in 1905 — the year he also explained the photoelectric effect.
🌙 Roughly how many hours of sleep do most adults need a night?
💡 Most sleep scientists put it at 7 to 9 hours for adults; teenagers need a bit more.
🇩🇰 Which Danish astronomer had an observatory on the island of Hven?
💡 Tycho Brahe measured the stars more accurately than anyone before telescopes.
🔬 Which gas do plants take in from the air?
💡 Plants use carbon dioxide and sunlight to make sugar, and give off oxygen.
🪐 Who was the first human in space?
💡 Gagarin orbited Earth on 12 April 1961.