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.
The Kuiper Belt. Dark, distant, and cold, the Kuiper Belt is the remote domain of an icy multitude of comet nuclei, that orbit our Sun in a strange, fantastic, and fabulous dance. Here, in the alien deep freeze of our Solar System's outer suburbs, the ice dwarf planet Pluto and its quintet of moons dwell along with a cornucopia of others of their bizarre and frozen kind. This very distant region of our Star's domain is so far from our planet that astronomers are only now first beginning to explore it, thanks to the historic visit to the Pluto system by NASA's very successful and productive New Horizons spacecraft on July 14, 2015. New Horizons is now well on its way to discover more and more long-held secrets belonging to this distant, dimly lit domain of icy worldlets.
Titan orbits Saturn once every 15 days and 22 hours. Like Earth's large Moon, in addition to many other moons in our Solar System, Titan's rotational period is precisely the same as its orbital period. This means that Titan only shows one face to its parent-planet, while the other face is always turned away.
Why hide these accomplishments? It has been difficult to argue for a conspiracy because no theory has offered a sufficiently convincing motive. An idea called "the frontier theory of history" provides two.