Europa, the moon of perpetual ice:Our Earth is often referred to as the Blue planet, and even though Europe is a moon, it gives us a run for our money. It is believed that Europa has an outer layer of water around 100 km mi) thick.
Like the sun, Jupiter is composed predominantly of hydrogen & helium. But unlike the sun, it lacks the necessary amount to begin fusion, the process that fuels a star. Jupiter would need to be 75-80 times more massive than it is at present to be considered a star. If all of the planets in the solar system had formed as part of the gas giant, it still would not have sufficient mass. Still, by itself, Jupiter is 2 & 1/2 times larger than all of the other planets in the solar system combined.
The first color movie of Jupiter from NASA's Cassini spacecraft shows what it would look like to peel the entire globe of Jupiter, stretch it out on a wall into the form of a rectangular map, and watch its atmosphere evolve with time. Credit: NASA/JPL/University of Arizona
The mystery of why Jupiter's Great Red Spot did not vanish centuries ago may now be solved, and the findings could help reveal more clues about the vortices in Earth's oceans and the nurseries of stars and planets, researchers say. The Great Red Spot is the most noticeable feature on Jupiter's surface — a storm about 12,400 miles (20,000 kilometers) long and 7,500 miles (12,000 km) wide, about two to three times larger than Earth. Winds at its oval edges can reach up to 425 mph (680 km/h).