Jupiter and its four planet-size moons, called the Galilean satellites, were photographed by Voyager 1 and assembled into this collage. They are not to scale but are in their relative positions.

His discovery advanced Nicolaus Copernicus' theory that cosmic objects did not revolve around ... found by historians show that Galileo identified the moons using Roman numerals - I, II, III ...

Initially believing they were distant stars, Galileo’s repeated observations over several nights and realized they were moons orbiting the gas giant. And thus, Io, Europa and Ganymede became ...

By Jan. 15, Galileo correctly concluded that he had discovered four moons orbiting around Jupiter, providing strong evidence for the Copernican theory that most celestial objects did not revolve ...

That's what Galileo did when he pointed his telescope ... the first observations of lunar craters, and the discovery of Jupiter's four largest moons. He even calculated the Sun's rotation period.

A new study has revealed that the Moon is far from geologically dead, with hundreds of newly discovered ridges suggesting that its surface is still shifting today. Scientists found evidence that ...

advertisement GALILEO: THE MAN WHO MOVED THE EARTH Imagine standing alone against an empire. That’s what Galileo did when he pointed his telescope at the heavens and declared that Earth wasn’t the ...

Discovery of the moon Deimos Moons are rare ... past decade or so is that Deimos and Phobos formed much like Earth's moon did, coalescing out of debris from a mighty impact on the planet.