Edmond Halley was an English astronomer. He went to the island of St. Helena. He went in 1676. He was just twenty years old. He wanted to make a list of the stars in the Southern Hemisphere. This had never been done before. He later studied comets. Comets are clouds of dust, ice, rock, and gas. They are frozen. Halley saw a comet in 1682. It was interesting. He noticed that its path was similar to the paths of other comets. It resembled a comet seen in 1607. It also resembled a comet seen in 1531. He guessed it would return in 1758. It returned. Halley’s Comet keeps reappearing. It reappears every 76 years.