Galileo Galilei

From Slackerpedia Galactica

One of the first carbon-based lifeforms on the planet Earth to use a telescope to look at things in the sky. He discovered that Jupiter had 4 moons that orbited it (now called the Galilean Moons in his honor), Saturn appeared to have "ears" (now known to be it's rings), and the Sun had spots.

Looking at the Sun with (or without) a telescope is now known to be not very bright or safe, so for goodness sake DON'T TRY THIS AT HOME. Even Galileo figured this out without first burning his retinas and projected the image of the sun.