Sol system (Sanctuary Stars)

  

Sol system

Sol and its planets (distances not to scale)
Age	4.568 billion years
Location	Local Bubble, Orion Arm, Milky Way
System mass	1.0014 Solar masses
Nearest star	Proxima Centauri (4.2441 ly)
Nearest known planetary system	Proxima Centauri system (4.2441 ly)
Planetary system
Semi-major axis of outer known planet (Neptune)	30.11 AU
Distance to Kuiper cliff	≈50 AU
Populations
Stars	1 (Sol)
Known planets	8: Mercury Venus Earth Mars Jupiter Saturn Apollo Neptune
Known dwarf planets	9: Ceres Orcus Pluto Haumea Quaoar Makemake Gongong Eris Sedna
Known natural satellites	657
Known minor planets	1.199 million
Known comets	4,402
Identified rounded satellites	19
Orbit about Galactic Center
Invariable-to-galactic plane inclination	≈60° (ecliptic)
Distance to Galactic Center	27,000 ly
Orbital speed	220 km/s
Orbital period	225-250 myr
Star-related properties
Spectral type	G2v
Frost line	≈5 AU
Distance to heliopause	≈120 AU
Hill sphere radius	≈1-3 ly

The Sol system (Lunar English: Sol; Martian Creole: Sülya; Apollonian: Sol) is the gravitationally-bound planetary system orbiting the yellow dwarf star Sol. Many thousands of objects orbit Sol, the largest of which are the eight planets. The innermost four of these planets are terrestrial: Mercury, Venus, Earth, and Mars. The outmost four planets are the gas giants Jupiter and Saturn, and the ice giants Apollo and Neptune. The Asteroid Belt divides the four innermost planets from the four outermost, while the Kuiper Belt divides interplanetary space from interstellar space.

Sol is approximately 4.6 billion years old and possesses an effective photosphere temperature of 5,772 Kelvin. Comprising about 99.86% of the mass of the entire system, Sol was formed by the collapse of matter within a region of a molecular cloud. The mass which did not accrete into the star itself became the remainder of the planetary system. All of the planets of the system orbit the star freely, and the only tidally locked bodies in the system are satellites of larger bodies. Throughout the Asteroid and Kuiper Belts there exist numerous dwarf planets in the Sol system, in addition to comets and other scattered planetesimals. Six of the major planets are orbited by moons; Jupiter's moon Ganymede and Saturn's moon Titan are both larger than, but neither more massive than, the smallest terrestrial planet, Mercury.

Humanity originated on the terrestrial planet Earth after the eons-long development of biological life on that planet. The Common Earth Calendar date of humanity's first space flight occurred in 1961 CEC, when cosmonaut Yuri Gagarin completed a single orbit of his home planet. In the centuries that followed this achievement, human life would spread from Earth to many other bodies in the system. The Third World War in the late 21st century culminated in the formation of Earth-Luna, otherwise preventing a major post-war collapse of human civilization. Among the most important colonies to be established by this early human space civilization were on Mars and Apollo. After a series of wars between Earth-Luna and Mars, the inner planets became united under the Tellurian Federation by the early 25th century. The arrival of the long-orbit Comet Ambrosia in 2612 and the ensuing Capitulatory War radically shifted the exopolitical balance of power towards Apollo, eventually resulting in the total unification of the Sol system under the Ecumene in 2642 CEC.

For almost a millennia and a half, the Sol system has served as the capital system of the Ecumene, an interstellar civilization led by the immortal Apollonians that spans more than five parsecs beyond the rim of the system. Apollo, the capital planet, is the political heart of the Sol system, while Earth and its moon Luna serve as a critical cultural, economic, and social cornerstone. Major centres of humanity are also located on Mars, the Jovian moons, Saturn's moon Titan, and throughout numerous space stations in the sytsem's two planetesimal belts. The Ecumenical Navy maintains a high degree of exopolitical power in the Sol system, such that the entirety of space within the heliosphere is firmly under Ecumenical control.

Etymology

The proper name for the star Sol comes from the extinct Latin language, which had been adopted as a major language of the system's scientific community over a thousand years before the present. The origin of the word traces back even further through ancient Latin to the Proto-Indo-European language, which is a linguistic precursor to a majority of common languages spoken across the system in the contemporary period. Inhabitants of the star system refer to Sol more typically by a vast number of common names, with the most popular simply being "the Sun" in Lunar English or the equivalent "o Sol" in Standard Apollonian.

The appellation Sol system refers more broadly to star and all of its satellite planets and planetesimals, while Sol (and likewise "the Sun" or "o Sol") alone refers specifically to the star. This naming structure is utilized across all of the Ecumene's star system possessions, with the first portion of the name being the star itself followed by the word "system." As with the inclusion of the dead Latin language into the Ecumene's scientific classification structure, the use of "system" is another ancient carry-over from over a thousand years before the present. In Lunar English, the whole collection of the star and its satellites is "the Sol system," while in Standard Apollonian it is "o Sol sistéma."

Exology

Sol

Sol, often referred to in-system as simply the Sun, is the eponymous star around which the planetary Sol system orbits. Sol is a G-type main-sequence star; being on the main sequence, Sol's large mass causes the hydrogen in its core to undergo nuclear fusion, producing helium and large amounts of energy in the form of visible, ultraviolet, and infrared light. This energy radiating from Sol is thought to be the most important factor in the sustenance of life on the planet Earth, from which modern Humanity originates.

The Sun is believed to have formed through the gravitational collapse of a large mollecular cloud approximately 4.6 billion Earth years ago; most of the matter gathered in the centre, forming the star, while the remaining matter flattened into a disc around the star that eventually became Sol's planetary system. When the hydrogen fusion in the core of Sol has subsided to the point that it can no longer sustain hydrostatic equilibrium, Sol's outer layers will begin to expand such that the innermost planets Mercury and Venus would be engulfed. By five billion years after the present, temperatures on Earth will be so extreme that it will no longer be able to sustain surface liquids. Eventually, the engorged outer layer will be shed in a cataclysmic supernova, leaving only a white dwarf stellar remnant.

As early as the most ancient records of human history, Sol has been recognized as a central feature of the natural world. Some early human civilizations worshipped Sol as a diety in its own right. The Earth's rotation on its axis relative to Sol creates a cycle of day and night that is intrinsic to the biological clock on which humans operate. The orbit of the Earth around Sol produces Earth's seasons and serves as the basis for the Common Earth Calendar utilized throughout Ecumene space in the contemporary day. In the era of human space civilization, the solar winds were a critical aspect of facilitating interplanetary travel through Solsailing, while the capture of Sol's light via SolGrid continues to serve as one of the system's largest sources of energy.

Mercury

Main article: Mercury (Sanctuary Stars)

Mercury is the smalllest planet in the Sol system. It has a mean radius of 0.3829 Er, a mass of 0.055 Em, and a gravity of 0.38 g. This makes it smaller than the two largest natural satellites in the Sol system, Ganymede and Titan, although it is still more massive than both. A terrestrial world, its surface is rocky and silicate in nature. Mercury's atmosphere is virtually non-existent, giving its surface a heavily marred appearance due to millennia of impact events. As the closest planet to the Sun at a mere 0.307 AU perihelion, it also experiences extreme variations in temperature, ranging from -173ºC at night to 427ºC at day. Mercury turns on its axis with a 3:2 spin-orbit resonance to the Sun, meaning it rotates on its axis three times for every two times it completes a revolution.

Mercury was first targeted for permanent human habitation relatively late compared to other bodies in the Sol system due to the extreme delta-v required to achieve orbit around the planet; although it had been visited as early as the 22nd century, it was not until the late 25th century CEC that settlement began in earnest. The Mercurian Ring was constructed around Mercury's meridian longitude beginning in the 26th century CEC, with massive solar arrays being built between this meridian region. During an optimal positioning of one entire array beneath the Sun in the middle of the Mercurian day, the planet generates up to 7.7% of the SolGrid's total energy output. As of the early 41st century CEC, Mercury had a total population of about 221.72 million, the fourth-largest of the planets behind Earth, Apollo, and Mars respectively.

Venus

Main article: Venus (Sanctuary Stars)

Venus is the third-smallest planet in the Sol system, with a comparable size to Earth. It has a mean radius of 0.9488 Er, a mass of 0.815 Em, and a gravity of 0.904 g. Like the other four innermost planets, Venus is a terrestrial world of a variable rocky, silicate substance. Venus experiences active volcanism, and its internal structure is similar to that of Earth's with a solid-molten mixed internal structure with a distinct core, mantle, and crust. Venus has extreme atmospheric conditions that cause its gaseous atmosphere to possess the qualities of a supercritical fluid a ground-level; temperature and pressure near ground level average 464ºC and 93 bar respectively. The atmosphere is composed primarily of carbon dioxide and is extensively covered by clouds of sulphuric acid. Scientific consensus as of the 41st century holds that these conditions are the after-effects of a past runaway greenhouse effect.

Through humanity's entire history, Venus has long been of astronomical significance. From Earth, Venus appears in ancient cultural understanding as both the evening star and the morning star since time immemorial, although by -550 CEC it began to be recognized as a singular celestial body. Venus was the first planet on which a human-made scientific craft made a soft landing in 1975 CEC, but soon after it became widely recognized that Venus' extreme conditions made it highly unsuitable for human exploration. The first humans to enter the planet's atmosphere around the early 22nd century largely avoided descending deep into its corrosive clouds. It would not be until the emergence of the Tellurian Federation in the 25th century that interest in the planet became more substantial. Most of the modern habitation of Venus in the 41st century consists of buoyant, atmospheric modules such as those found on the outer gas giants. Venus is one of two insignificantly inhabited planets in the Sol system alongside Jupiter, with an average yearly population exceeding no more than one million persons.

History

Main article: History of human space civilization (Sanctuary Stars)

Society

Politics

The emblem of the Ecumene, which established political control over the whole Sol system in 2642 CEC following the Conference of Planets and Moons.

See also

• Ecumene
• Human inhabited space
  • Alpha Centauri system
  • Amaro system
  • Amaterasu system
  • Canaan system
  • Gliese 1061 system
  • Hades system
  • Ross 128 system
  • Teegarden system