Edmond Halley was an English astronomer. Studying records of past comets, he predicted that the comet that appeared in 1682 would return about every 76 years. It reappeared as predicted at the end of 1758, after his death, and was named “Halley’s Comet.” He is also known for helping publish Newton’s Principia and for serving as Astronomer Royal.
In 1692, to explain why the direction a compass points changes over the years, he proposed that the Earth’s interior consists of nested shells. This is considered the beginning of the hollow Earth theory by a scientist.
