Solar System 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
Alien Legacy of the system. The Beta Caeli system is similar to our real-life solar system, with a barren, rocky inner planet, terrestrial planets in the habitable zone of the inner system, followed by gas giants in the outer system that first increase and then decrease in size, and a tiny rock outermost. The naming of the Caelian planets closely matches that of naming planets in our solar system. But while our system uses the names of Roman deities (except for Uranus), Caeli has Greek ones; Gaea is the Greek goddess of the Earth, and Rhea is her daughter. In addition, as