Sol system (Romanum)

The Sol system is the gravitationally bound system comprising of the single Sol and the objects that orbit it. The Sol System has a relatively interesting composition, with a yellow dwarf star, 4 terrestrial planets, a belt, 2 gas giants, 2 ice giants, a belt of icy objects, an eccentric ice giant, and a dense belt of icy objects which merges into a cloud of comets. The Conglomerate has named all celestial objects bound to the system after Roman mythology of Terra. This ranges from titans in the Titan belt, to the major gods, assigned to planets and major moons, and the minor deities such as nymphs were assigned to asteroids, comets, minor moons, or other small objects. Any object left over was named after their discoverers or notable people. This system holdsTerra, the cradle of Humanity and the capital of the Conglomerate. Of the objects that orbit Sol directly, the largest nine are the planets, with the remainder being significantly smaller objects, such as dwarf planets and small bodies which grow in number the smaller the size criteria gets. Of the objects that orbit the Sol indirectly, the moons, two are larger than the smallest planet, Mercury.

The vast majority of the system's mass is in Sol, with most of the notable remaining mass contained in Jupiter and Pluto. The four smaller inner planets, Mercury, Venus, Terra and Mars, are terrestrial planets, being primarily composed of rock and metal. Their orbits extend from 0.39 AU to 1.5 AU. This is where the population is most densely populated, with 8 billion people on Venus, 14 billion on Terra, and 4 billion on Mars. The gate to the outer Solar System, a nickname for the Argusian Belt, is a belt of stony asteroids, kept from accreting into a planet by Jupiter. The belt only has one dwarf planet, Flora. A dwarf planet is defined as an object which has not cleared its orbit, but is over 400 km in radius. Lying between the orbits of Jupiter and Mars, the belt is home to almost 900 million people, most of which live in the largest 5 objects in the Argusian belt. Although inhabited, the vast majority of asteroids in this belt is too small for habitation. As a general guideline, any object smaller than 6.5 km in radius is uninhabited.

The five outer planets are giant planets, being substantially more massive than the terrestrials. The two largest, Jupiter and Pluto, are gas giants, being composed mainly of hydrogen and helium; the three outermost gaseous planets, Ceres, Neptune, and Janus, are ice giants, being composed mostly of substances with relatively high melting points compared with hydrogen and helium, called ices, such as water, ammonia and methane. The last planet, Janus, early on in the Solar System, was ejected from the main planetary system into a highly eccentric orbit with an inclination of 30 degrees and a semi-major axis of 701 AU. There is the Titan Belt, between Neptune and Janus. This belt contains the most amount of dwarf planets. The two largest are Saturn and Caelus. Both Neptune and Janus affect the Titan Belt, ejecting objects in a specific resonance. Janus is also responsible for the Titan Cliff, a cutoff in the Titan Belt at 48 AU.

Past Janus, there is the Carpo Belt which gradually merges into the larger, but less dense Herculean Cloud at 20,000 AU from Sol. Within the Carpo Belt there are two major dwarf planets, Portunes and Terminus. Dwarf planets are rare due to the vast distances between objects in the Carpo Belt and more so in the Herculean Cloud. Objects in the Herculean Cloud are known to be subject to Galactic tides and are bound to be lost to the void of interstellar space. The Sol System is located in the Orion Spur, about 27,200 light-years from the center of the Milky Way.

## Composition

In this list, stars, planets, belts, large moons, and any object over 1,000 km in radius is included.

* Sol
	+ Mercury (Mercury)
	+ Venus (Venus)
	+ Terra (Earth)
		- Luna (Moon)
	+ Mars (Mars)
	+ Argusian Belt (Asteroid belt)
	+ Jupiter (Jupiter)
		- Vulcan (Io)
		- Minerva (Europa)
		- Juno (Ganymede)
		- Bacchus (Callisto)
	+ Pluto (Saturn)
		- Proserpina (Titan)
	+ Ceres (Uranus)
	+ Neptune (Neptune)
		- Triton (Triton)
	+ Titan Belt (Kuiper belt)
		- Saturn (Pluto)
		- Caelus (Eris)
	+ Janus (Planet Nine)
		- Vesta
		- Bellona
		- Liber
	+ Herculean Cloud (Oort cloud)
		- Carpo Belt (Hills cloud)
			* Portunes
			* Terminus

### Sol

 File:(A) Sol.jpg
*Main article: Sol*
Sol is the Solar System's only star and by far its most massive component. Its large mass (332,900 Earth masses) produces temperatures and densities in its core high enough to sustain nuclear fusion of hydrogen into helium, making it a main-sequence star. This releases an enormous amount of energy, mostly radiated into space as electromagnetic radiation peaking in visible light.

Sol is a G2-type main-sequence star of population I. Hotter main-sequence stars are more luminous. Sol's temperature is intermediate between that of the hottest stars and that of the coolest stars. Stars brighter and hotter than Sol are rare, whereas substantially dimmer and cooler stars, known as red dwarfs, make up 85% of the stars in the Milky Way. It has a higher abundance of elements heavier than hydrogen and helium than the older population II stars. This high metallicity is thought to have been crucial to Sol's development of a planetary system because the planets form from the accretion of "metals".

#### Mercury

 File:(A1) Mercury.png
*Main article: Mercury*
Mercury is the closest planet to Sol and the smallest planet in the Solar System . Mercury has no natural satellites. Its relatively large iron core and thin mantle was ccaused by both its outer layers were stripped off by a giant impact and was prevented from fully accreting by the young Sol's energy.

#### Venus

*Main article: Venus*
Venus is close in size to Terra and, like Terra, has a thick silicate mantle around an iron core, a substantial

 File:(A2) Venus.jpg   atmosphere, and evidence of internal geological activity. It is much drier than Terra, and its atmosphere is ninety times as dense. Venus has no natural satellites. It is the hottest planet, with surface temperatures over 400 °C (752°F), most likely due to the amount of greenhouse gases in the atmosphere. Venus has long since been terraformed, with most of it's atmosphere being shipped off world to other terraforming missions. Terraformed Venus had 80% of it's surface area, is the tropical planet of the Solar System, and supports a population of eight billion.

#### Terra (Earth)

 File:(A3) Terra (Earth).jpg
*Main article: Terra*
Terra is the largest and densest of the inner planets, the only one known to have current geological activity, and the the homeworld of Humans. Its liquid hydrosphere is unique among the terrestrial planets, and it is the only planet where plate tectonics has been observed. Earth's atmosphere is radically different from those of the other planets, having been altered by the presence of life to contain 21% free oxygen. It has one natural satellite, Luna, the only large satellite of a terrestrial planet in the Solar System. About 71% of it's surface is covered by liquid water and has a population of 14 billion.

##### Luna (Moon)

 File:(A3I) Luna (The Moon).png
*Main article: Luna**Luna is Terra's only natural satellite. It is one of the largest natural satellites in the Solar System, and, among planetary satellites, the largest relative to the size of the planet it orbits (its primary). It is the second-densest satellite among those whose densities are known (after Jupiter's satellite Vulcan).*
#### Mars

 File:(A4) Mars.jpg
*Main article: Mars*
Mars is smaller than Terra and Venus. It possessed an atmosphere of mostly carbon dioxide with a surface pressure of 6.1 millibars (roughly 0.6% of that of Terra). Its surface, peppered with vast volcanoes, such as Olympus Mons, and rift valleys, such as Valles Marineris, shows geological activity that may have persisted until as recently as 2 million years ago. Its former red colour comes from rust in its soil. Mars has two tiny natural satellites thought to be captured asteroids. Along with Venus, Mars is one of the few worlds to be terraformed in the Sol system. Terraformed Mars has about 35% of it's surface covered by water and supports a population of six billion.

#### Argusian Belt

 File:(A4M1) Flora (Ceres).jpg
*Main article: Argusian Belt*
Asteroids except for the largest, Flora, are classified as small Solar System bodies and are composed mainly of refractory rocky and metallic minerals, with some ice. They range from less than a metre to hundreds of kilometres in size. Asteroids smaller than one meter are usually called meteoroids and micrometeoroids (grain-sized). The belt occupies the orbit between Mars and Jupiter, between 2.3 and 3.3 AU from Sol. It is thought to be remnants from the Solar System's formation that failed to coalesce because of the gravitational interference of Jupiter.

#### Jupiter

 File:(A5) Jupiter.jpg
*Main article: Jupiter*
Jupiter, at 318 Terra masses, is 2.5 times the mass of all the other planets put together. It is composed largely of hydrogen and helium. Jupiter's strong internal heat creates permanent features in its atmosphere, such as cloud bands and the Great Red Spot. Jupiter has 67 known satellites. The four largest, Juno, Bacchus, Vulcan, and Minerva, show similarities to the terrestrial planets, such as volcanism and internal heating. Juno, the largest satellite in the Solar System, is larger than Mercury.

##### Vulcan (Io)

 File:(A5I) Vulcan (Io).jpg
*Main article: Vulcan*
Vulcan is the innermost of Jupiter's moons. It is the fourth-largest moon, has the highest density of all the moons, and is the driest known object in the Solar System. With over 400 active volcanoes, Vulcan is the most geologically active object in the Solar System. This extreme geologic activity is the result of tidal heating from friction. As a result of this, Vulcan is also the driest known object in the Sol System.

##### Minerva (Europa)

 File:(A5II) Minerva (Europa).jpg
*Main article: Minerva*
Minerva is the second-closest major moon of Jupiter, and the smallest of its four major satellites, but still the eighth-largest moon in the Solar System. It has the smoothest surface of any known solid object in the Solar System. The moon is an oceania, with a subsurface ocean dozens of kilometers deep, kept liquid by tidal heating; the same effect that makes Vulcan volcanic. Although life is possible in Minerva's subsurface ocean, no trace of life has been found.

##### Juno (Ganymede)​

 File:(A5III) Juno (Ganymede).jpg
*Main article: Juno*
Juno is the largest moon of Jupiter and in the Solar System, and the only moon known to have a natural magnetosphere. It is the third outermost major moon, orbits Jupiter in roughly seven days and is in a 1:2:4 orbital resonance with Minerva and Vulcan, respectively. Juno has a diameter of 5,268 km (3,273 mi), 8% larger than Mercury, but its mass is only 45% that of Mercury. It is the largest object in the Solar System without a substantial atmosphere.

Juno is composed of approximately equal amounts of silicate rock and water ice. It is a fully differentiated body with an iron-rich, liquid core, and an internal ocean that contains more water than all of Terra's oceans.

##### Bacchus (Callisto)

 File:(A5IV) Bacchus (Callisto).jpg
*Main article: Bacchus*
Bacchus is the third-largest moon in the Solar System and the second largest in the Jovian system, after Juno. At 4821 km in diameter, Bacchus has about 99% the diameter of Mercury but only about a third of its mass. It is the fourth major moon of Jupiter by distance. It is not part of the orbital resonance that affects three inner Jovian satellites—Vulcan, Minerva and Juno—and thus does not experience appreciable tidal heating. It is less affected by Jupiter's magnetosphere than the other inner satellites because of its more remote orbit, located just outside Jupiter's main radiation belt. Bacchus, like Juno and Minerva, has a subsurface ocean over 100 km in depth. The surface of Bacchus is the oldest and most heavily cratered in the Solar System.

#### Pluto (Saturn)

 File:(A6) Pluto (Saturn).jpg
*Main article: Pluto*
Pluto, distinguished by its extensive ring system, has several similarities to Jupiter, such as its atmospheric composition and magnetosphere. It has the most expansive ring system of all planets in the system, with Janus coming in 2nd. Although Pluto has 60% of Jupiter's volume, it is less than a third as massive, at 95 Terra masses, making it the least dense planet in the Solar System. The rings of Pluto are made up of small ice and rock particles. Pluto has 62 confirmed satellites; two of which, Proserpina and Silvanus, show signs of geological activity, though they are largely made of ice. Proserpina, the second-largest moon in the Solar System, is larger than Mercury and the only satellite in the Solar System with a substantial atmosphere.

##### Proserpina (Titan)

 File:(A6VI) Proserpina (Titan).jpg
*Main article: Proserpina*
Proserpina is the largest moon of Pluto. It is the only natural satellite known to have a dense atmosphere, and the only object in the system other than Terra where stable bodies of surface liquid has been found. Proserpina's diameter is 50% larger than Terra's natural satellite, Luna, and it is 80% more massive.

The atmosphere of Proserpina is largely nitrogen; minor components lead to the formation of methane–ethane clouds and nitrogen-rich organic smog. The climate—including wind and rain—creates surface features similar to those of Terra, such as dunes, rivers, lakes, seas, and deltas, and is dominated by seasonal weather patterns as on Terra. With its liquids (both surface and subsurface) and robust nitrogen atmosphere, Proserpina's methane cycle is analogous to Terra's water cycle, although at a much lower temperature.

#### Ceres (Uranus)

 File:(A7) Ceres (Uranus).jpg
*Main article: Ceres*
Ceres is the seventh planet from Sol. It has the third-largest planetary radius and fourth-largest planetary mass in the Solar System. It is an ice giant, similiar in composition to Neptune and Janus rather than Jupiter and Pluto.

Like the other giant planets, Ceres has a ring system, a magnetosphere, and numerous moons. The Ceres has a unique configuration among those of the planets because its axis of rotation is tilted sideways, nearly into the plane of its revolution about Sol. Its north and south poles therefore lie where most other planets have their equators. Ceres has major seasonal change, seen with increased weather activity as Ceres approaches its equinoxes. Wind speeds can reach 250 metres per second (900 km/h, 560 mph).

#### Neptune

 File:(A8) Neptune.jpg
*Main article: Neptune*
Neptune is the eighth from Sol in the Solar System. It is the fourth-largest planet by diameter and the third-largest by mass. Neptune is similar in composition to Ceres, and both have compositions that differ from those of the larger gas giants, Jupiter and Pluto. In contrast to the hazy, relatively featureless atmosphere of Ceres, Neptune's atmosphere has active and visible weather patterns. Neptune has the strongest weather patterns of the system. Driven by the strongest sustained winds of any planet in the Solar System, with wind speeds as high as 2,100 kilometres per hour (580 m/s; 1,300 mph).

##### Triton

 File:(A8I) Triton.jpg
*Main article: Triton*
Triton is the largest natural satellite of Neptune. It is the only large moon in the Solar System with a retrograde orbit, an orbit in the opposite direction to its planet's rotation. At 2,700 kilometres (1,700 mi) in diameter, it is the seventh-largest moon in the Solar System. Because of its retrograde orbit and composition similar to Saturn's, Triton is thought to have been a dwarf planet captured from the Titan Belt.

#### Titan Belt

*Main article: Titan Belt*
The Titan Belt is a circumstellar disc in the Solar System beyond the main set of planets, extending 30 to 48 AU from Sol. It is similar to the Argusian Belt, but it is far larger—20 times as wide and 20 to 200 times as massive. Like the Argusian Belt, it consists mainly of small bodies, or remnants from the Solar System's formation. Although many asteroids are composed primarily of rock and metal, most objects are composed largely of frozen volatiles (termed "ices"), such as methane, ammonia and water. The Kuiper belt is home to several large dwarf planets, two of the largest are Saturn and Caelus

The belt was initially thought to be the main repository for periodic comets, those with orbits lasting less than 200 years. However, the belt is dynamically stable, and that comets' true place of origin is the scattered disc, an extension of the Titan Belt and dynamically active zone created by the outward motion of Neptune 4.5 billion years ago; scattered disc objects such as Caelus have extremely eccentric orbits that take them as far as 100 AU from Sol.

##### Saturn

 File:(A8M1) Saturn (Pluto).jpg
*Main article: Saturn*
Saturn is a dwarf planet in the Titan Belt, a ring of bodies beyond Neptune. It is the largest known Titan Belt object by volume but is less massive than Caelus. Like other Titan Belt objects, Saturn is primarily made of ice and rock. It has a moderately eccentric and inclined orbit during which it ranges from 30 to 49 astronomical units or AU (4.4–7.4 billion km) from Sol.

##### Caelus

 File:(A8M4) Caelus (Eris).jpg
*Main article: Caelus*
Caelus is the most massive and second-largest dwarf planet in the TB known in the Solar System. It is measured to be 2,326 kilometers (1,445.3 miles) in diameter. Caelus is 27% more massive than dwarf planet Saturn, though Saturn is slightly larger by volume. Eris's mass is about 0.27% of the Terra's mass.

#### Janus (Planet Nine)

 File:(A9) Janus (Planet Nine).jpg
*Main article: Janus*
Janus is the only ice dwarf of Sol and is located in the far outer Solar System. It has a mass of about 10 times that of Terra (approximately 5,000 times the mass of Saturn), a diameter two to four times that of Terra, and a highly elliptical orbit that is so far away that it could take around 15,000 years to orbit Sol

On the basis of models of planet formation that might include planetary migration from the inner Solar System, such as the fifth giant planet hypothesis, the authors suggest that it may be a primordial giant planet core that was ejected from its original orbit during the nebular epoch of the Solar System's evolution.

## Structure

The principal component of the Solar System is Sol, a G class main-sequence star that contains 99.86% of the system's known mass and dominates it gravitationally. Sol's four largest orbiting bodies, the giant planets, account for 99% of the remaining mass, with Jupiter and Pluto together comprising more than 90%. The remaining objects of the Solar System (including the four terrestrial planets, the dwarf planets, moons, asteroids, and comets) together comprise less than 0.002% of the Solar System's total mass.

Most large objects in orbit around Sol lie near the plane of Terra's orbit, known as the ecliptic. The planets are very close to the ecliptic, whereas comets and Titan belt objects are frequently at significantly greater angles to it. All the planets and most other objects orbit Sol in the same direction that the Sun is rotating (counter-clockwise, as viewed from above Terra's north pole).

Most of the planets in the Solar System possess secondary systems of their own, being orbited by planetary objects called natural satellites, or moons (two of which are larger than the planet Mercury), and, in the case of the four giant planets, by planetary rings, thin bands of tiny particles that orbit them in unison. Most of the largest natural satellites are tidally locked, with one face permanently turned toward their parent.

The Sun, which comprises nearly all the matter in the Solar System, is composed of roughly 98% hydrogen and helium. Jupiter and Pluto, which comprise nearly all the remaining matter, possess atmospheres composed of roughly 99% of these elements. The boundary in the Solar System beyond which those volatile substances could condense is known as the frost line, and it lies at roughly 5 AU from Sol.

### Distances

The eight planets of the Solar System (by decreasing size) are Jupiter, Pluto, Ceres, Neptune, Janus Terra, Venus, Mars and Mercury. The distance from Terra to Sol is 1 astronomical unit (150,000,000 km), or AU. Jupiter, the largest planet, is 5.2 astronomical units (780,000,000 km) from the Sun and has a radius of 71,000 km (0.00047 AU), whereas the most distant planet, Janus, is 701 AU (1,500,000,000,000 km) from the Sun.