What discoveries is Jean Foucault, French Physicist and astronomer, noted for?
Jean Foucault is noted mainly for his proof that light travels more slowly in water than in air, and his measurement of the speed of light. In 1851, he proved that the Earth rotates by using a freely suspended pendulum and studying the way it swings from side to side. He also invented the gyroscope and some optical instruments.
Name the Danish astronomer who detected serious mistakes in the astronomical tables of his time and revised them.
Tycho Brahe, originally studied law, but was more interested in astronomy. In 1563, he discovered serious mistakes in the astronomical tables then in use. He did much important work on the movement of the stars and the Moon.