Jupiter
(Muhammad Unza Farooqui, Karachi)
Jupiter is the fourth brightest
object in the sky (after the Sun, the Moon and Venus). It has been known since
prehistoric times as a bright "wandering star". But in 1610 when Galileo first
pointed a telescope at the sky he discovered Jupiter's four large moons Io,
Europa, Ganymede and Callisto (now known as the Galilean moons) and recorded
their motions back and forth around Jupiter. This was the first discovery of a
center of motion not apparently centered on the Earth. It was a major point in
favor of Copernicus's heliocentric theory of the motions of the planets (along
with other new evidence from his telescope: the phases of Venus and the
mountains on the Moon). Galileo's outspoken support of the Copernican theory got
him in trouble with the Inquisition. Today anyone can repeat Galileo's
observations (without fear of retribution :-) using binoculars or an inexpensive
telescope.