... English astronomer and mathematician. ... American astronomer. ... Bond, William Cranch 1789-1859 . ... At the observatory, he studied Saturn and (with William Lassell ) discovered its moon Hyperion . ... Polish astronomer who advanced the heliocentric theory that the earth and other planets revolve around the Sun. ... Galileo Galilei 1564-1642 . ... Van Allen discovered the Earth's radiation belts, which now bear his name, with an instrument aboard the first successful American satellite, Explorer...