Earth and its Water Over 70% of the Earth’s surface is glazed with glistening ocean. This, of course, is where the phrase ‘The Blue Marble’ originated from. All this water accounts to a total volume equal to 1.3 billion cubic kilometres – but did you know that according the model of the Sun’s proto-planetary disk, Earth actually has a deficit of this familiar and life sustaining substance? Astronomers studying how the Earth initially formed have been stuck tryin
"Callisto, Jupiter's moon-Spectacular! According to NASA, it has the darkest surface of the four Galilean moons, but is twice as bright as our moon :) It is also the most heavily cratered object in the entire solar system!"