(1889-1953) a US astronomer (= scientist who studies the stars, planets, etc.). He was the first to find evidence that the universe is becoming larger in size. He did this in 1929 when he discovered that galaxies (= very large groups of stars) move away from us in a regular way. This is now called Hubble's Law. In 1923, he had discovered that large galaxies exist beyond our own. His research was done at the Mount Wilson Observatory in California. The Hubble Space Telescope is named after him.