The Solar System formed 4. 6 billion years ago from the gravitational collapse of a giant interstellar molecular cloud. The vast majority of the system’s mass is in the Sun, with the majority of the remaining mass contained in Jupiter. The four smaller inner planets, Mercury, Venus, Earth and Mars, are terrestrial planets, being primarily composed of rock and metal. The four outer planets are giant planets, being substantially more massive than the terrestrials. The two largest, Jupiter and Saturn, are gas giants, being composed mainly of hydrogen and helium; the two outermost planets, Uranus and Neptune, are ice giants, being composed mostly of substances with relatively high melting points compared with hydrogen and helium, called volatiles, such as water, ammonia and methane. All eight planets have almost circular orbits that lie within a nearly flat disc called the ecliptic.
However, Dr. Thomas explained to the press in May 2013 that the ring arcs are much more tenuous than the fully formed rings of Saturn. As a matter of fact, the ring arcs are so delicate and thin that it would take about ten billion years for just 1 meter of blowing icy snow to collect within the craters of Methone. Had Jupiter continued to gain weight, it would have grown ever hotter and hotter, and ultimately self-sustaining, raging nuclear-fusing fires may have been ignited in its heart. This would have sent Jupiter down that long, shining stellar road to full-fledged stardom. Had this occurred, Jupiter and our Sun would have been binary stellar sisters, and we probably would not be here now to tell the story. Our planet, and its seven lovely sisters, as well as all of the moons and smaller objects dancing around our Star, would not have been able to form. However, Jupiter failed to reach stardom. After its brilliant, sparkling birth, it began to shrink. Today, Jupiter emits a mere.00001 as much radiation as our Sun, and its luminosity is only.0000001 that of our Star. "The rectangular pattern of gravity anomalies was completely unexpected. Using the gradients in the gravity data to reveal the rectangular pattern of anomalies, we can now clearly and completely see structures that were only hinted at by surface observations," Dr. Jeffrey Andrews-Hanna explained in the October 1, 2014 NASA Press Release. Dr. Andrews-Hanna, a GRAIL co-investigator at the Colorado School of Mines in Golden, Colorado, is lead author of the paper.