UFO must be joking

Written in the stars: We’ve been searching for aliens for longer than you’d think. We got our first decent look at the night sky in the early 1600s, when Galileo Galilei built a telescope strong enough to use for astronomy. After stargazers spotted dark shadows on the moon, many believed they were oceans teeming with life.

Space oddities: Born in 1724, Immanuel Kant was convinced the six known planets in the solar system were full of extraterrestrials. The philosopher thought these creatures were arranged in order of intelligence, with the thickest on Mercury, brainiest on Saturn.

Place in the sun: Astronomer William Herschel, who discovered Uranus in 1781, was a committed alien believer who thought every celestial body was inhabited – including the sun. Rather than a star, he claimed it was a planet with a fiery atmosphere. He said the “solarians” who lived there had adapted to the extreme heat.