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.
Some astronomers think that the two gas-giants do not sport solid surfaces secreted beneath their immense and heavy gaseous atmospheres, although others suggest that the jumbo-size duo do, indeed, harbor relatively small cores of rocky-icy stuff. The two other large inhabitants of the outer limits of our Sun's family are Uranus and Neptune, which are both classified as ice-giants, because they harbor large icy cores secreted deep down beneath their heavy, dense gaseous atmospheres which, though very massive, are not nearly as heavy as the gaseous envelopes possessed by Jupiter and Saturn.
Makemake is a classical KBO. This means that its orbit is situated far enough away from Neptune to remain in a stable stage over the entire age of our more than 4 billion year old Solar System. Classical KBOs have perihelia that carry them far from the Sun, and they are also peacefully free from Neptune's perturbing influence. Such objects show relatively low eccentricities and circle our Star in a way that is similar to that of the major planets. However, Makemake is a member of what is referred to as a "dynamically hot" class of classical KBOs, which instead display a high inclination when compared to other classical KBOs.
As of December 2015, confirmed liquid water in our own Solar System--excluding Earth--accounts for about 25 to 50 times the volume of our planet's water. The moons of our Sun's family thought to possess liquid water are: