Pacifica System (Pacifica)

The Pacifica System or Solar System is the gravitationally bound system of the Sun and the objects that orbit it, either directly or indirectly, including Pacifica. Of the objects that orbit the Sun directly, the largest are the nine planets, with the remainder being smaller objects, the dwarf planets and small Solar System bodies.

The Pacifica 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 Visi. The four smaller inner system planets, Parva, Proxima, Pacifica and Tyr, are terrestrial planets, being primarily composed of rock and metal, while the innermost planet, Clara, is a gas giant. The four outer system planets are giant planets, being substantially more massive than the inner system planets. The two largest planets, Visi and Porea, are gas giants, being composed mainly of hydrogen and helium; the two outermost planets, Tillsi and Xion, are a massive rocky planet and an ice giant respectively, being composed mostly of substances with relatively high melting points compared with hydrogen and helium, called volatiles, such as water, ammonia and methane. All nine planets have almost circular orbits that lie within a nearly flat disc called the ecliptic.

The Pacifica System also contains smaller objects. The innermost asteroid belt, the Balteuma Belt, which lies between the orbits of Parva and Proxima, mostly contains objects composed, like the terrestrial planets, of rock and metal. Within these populations, some objects are large enough to have rounded under their own gravity; such objects are categorized as dwarf planets. The largest dwarf planet is Balteuma. Beyond Porea lie the Botnienn Belt which is a population of objects composed mostly of small asteroids and ices. Beyond Xion lies Hachiman's Keep and the scattered disc, which also is a population of objects composed mostly of small ices and beyond them a newly discovered population of sednoids. It is possible that several dwarf planets lie here, but none have been found yet. In addition to these three regions, various other small-body populations, including comets, centaurs and interplanetary dust clouds, freely travel between regions. Six of the planets and many of the smaller bodies are orbited by natural satellites, usually termed "moons" after the Moon (Maxima). Each of the outer planets is encircled by planetary rings of dust and other small objects.

The solar wind, a stream of charged particles flowing outwards from the Sun, creates a bubble-like region in the interstellar medium known as the heliosphere. The heliopause is the point at which pressure from the solar wind is equal to the opposing pressure of the interstellar medium; it extends out to the edge of the scattered disc. The Cloud, which is thought to be the source for long-period comets, may also exist at a distance roughly a thousand times further than the heliosphere. The Solar System is located 26,000 light-years from the center of the galaxy in the Arm, which contains most of the visible stars in the night sky. The nearest stars are within the so-called Local Bubble, with the closest at 4.25 light-years.

Structure and composition

Planets

The 2006 International Astronomical Union (IAU) defines a planet as a body in orbit around the Sun that was large enough to have achieved hydrostatic equilibrium and to have "cleared the neighbourhood around its orbit". The practical meaning of "cleared the neighbourhood" is that a planet is comparatively massive enough for its gravitation to control the orbits of all objects in its vicinity. By the IAU's definition, there are nine planets in the Solar System; five terrestrial planets (Parva, Proxima, Pacifica, Tyr and Tillsi) and four giant planets, which can be divided further into two gas giants (Clara, Visi and Porea) and one ice giant (Xion). When excluding the Sun, the four giant planets account for more than 99% of the mass of the Solar System.

Comprehensive overview of the Pacifica System. The Sun, planets, dwarf planets and moons are at scale for their relative sizes, not for distances. A separate distance scale is at the bottom. Moons are listed near their planets by proximity of their orbits; only the largest moons are shown.

Key
* Terrestrial planet	° Gas giant	‡ Ice giant

		°Clara	*Parva	*Proxima	*Pacifica	*Tyr	°Visi	°Porea	*Tillsi	‡Xion
Symbols
Mean distance from the Sun	km AU	57,909,175 0.38709893	91,977,591 0.61483219	124,440,270 0.83183179	149,597,890 1.00000011	227,936,640 1.52366231	778,412,010 5.20336301	1,426,725,400 9.53707032	2,870,972,200 19.19126393	4,498,252,900 30.06896348
Equatorial radius	km :E	25,559 4.007	3,073.8 0.48195	3,488.7 0.54698	6,378.1366 1	3,396.19 0.53247	71,492 11.209	60,268 9.449	13,680.8 2.145	24,764 3.883
Mass	kg :E	8.6594×1025 14.5	6.604×1023 0.11	3.906×1023 0.165	5.972×1024 1	6.4191×1023 0.107	1.9708×1027 330	6.091×1026 102	5.924×1025 9,92	1.0809×1026 18,1
Number of known moons		1	0	0	2: Maxima and Minima	0	79	82	27	14
Rings?		No	No	No	No	No	Yes	Yes	Yes	Yes