Following the discovery of the planet Neptune in 1846, there was considerable speculation that another planet might exist beyond its orbit. The search began in the mid-19th century and continued at the start of the 20th with Percival Lowell's quest for Planet X. Lowell proposed the Planet X hypothesis to explain apparent discrepancies in the orbits of the giant planets, particularly Uranus and Neptune, speculating that the gravity of a large unseen ninth planet could have perturbed Uranus enough to account for the irregularities.
The Solar System is the gravitationally bound system of the Sun and the objects that orbit it. It formed 4.6 billion years ago from the gravitational collapse of a giant interstellar molecular cloud. The vast majority (99.86%) of the system's mass is in the Sun, with most of the remaining mass contained in the planet Jupiter. The four inner system planets—Mercury, Venus, Earth and Mars—are terrestrial planets, being composed primarily of rock and metal. The four giant planets of the outer system are substantially larger and more massive than the terrestrials. The two largest, Jupiter and Saturn, are gas giants, being composed mainly of hydrogen and helium; the next two, Uranus and Neptune, are ice giants, being composed mostly of volatile substances with relatively high melting points compared with hydrogen and helium, such as water, ammonia, and methane. All eight planets have nearly circular orbits that lie near the plane of Earth's orbit, called the ecliptic.
Pluto is a dwarf planet in the Kuiper belt, a ring of bodies beyond the orbit of Neptune. It was the first object discovered in the Kuiper belt, in 1930. It was declared the ninth planet from the Sun, though it was always the odd object out. Following the discovery of additional objects in the Kuiper belt and scattered disc starting in the 1990s, particularly the more massive dwarf planet Eris, Pluto's status as a planet was increasingly questioned. In 2006 the International Astronomical Union (IAU) formally re-defined the term planet to exclude Pluto, which was classified as a dwarf planet.
The River Parrett flows through the counties of Dorset and Somerset in South West England, from its source in the Thorney Mills springs in the hills around Chedington in Dorset. Flowing northwest through Somerset and the Somerset Levels to its mouth at Burnham-on-Sea, into the Bridgwater Bay nature reserve on the Bristol Channel, the Parrett and its tributaries drain an area of 660 square miles (1,700 km2) – about 50 per cent of Somerset's land area, with a population of 300,000.
The Bridgwater and Taunton Canal is a canal in the south-west of England between Bridgwater and Taunton, opened in 1827 and linking the River Tone to the River Parrett. There were a number of abortive schemes to link the Bristol Channel to the English Channel by waterway in the 18th and early 19th centuries. These schemes followed the approximate route eventually taken by the Bridgwater and Taunton Canal, but the canal was instead built as part of a plan to link Bristol to Taunton by waterway.
In astronomy, the barycenter is the center of mass of two or more bodies that orbit one another and is the point about which the bodies orbit. A barycenter is a dynamical point, not a physical object. It is an important concept in fields such as astronomy and astrophysics. The distance from a body's center of mass to the barycenter can be calculated as a two-body problem.
North Petherton is a small town and civil parish in Somerset, England, situated on the edge of the eastern foothills of the Quantocks, and close to the edge of the Somerset Levels. The town has a population of 6,730 as of 2014. The parish includes Hamp, Melcombe, Shearston, Woolmersdon and Huntworth.
The River Tone is a river in the English county of Somerset. The river is about 33 kilometres (21 mi) long. Its source is at Beverton Pond near Huish Champflower in the Brendon Hills, and is dammed at Clatworthy Reservoir. The reservoir outfall continues through Taunton and Curry and Hay Moors, which are designated as a Site of Special Scientific Interest. Finally, it flows into the River Parrett at Burrowbridge.
Nine Views is an ambiental installation in Zagreb, Croatia which, together with the sculpture Prizemljeno Sunce, comprises a scale model of the Solar System.
The Sweden Solar System is the world's largest permanent scale model of the Solar System. The Sun is represented by the Avicii Arena in Stockholm, the largest hemispherical building in the world. The inner planets can also be found in Stockholm but the outer planets are situated northward in other cities along the Baltic Sea. The system was started by Nils Brenning, professor at the Royal Institute of Technology in Stockholm, and Gösta Gahm, professor at the Stockholm University. The model represents the Solar System on the scale of 1:20 million.
The formation of the Solar System began about 4.6 billion years ago with the gravitational collapse of a small part of a giant molecular cloud. Most of the collapsing mass collected in the center, forming the Sun, while the rest flattened into a protoplanetary disk out of which the planets, moons, asteroids, and other small Solar System bodies formed.
The International Astronomical Union (IAU) defined in August 2006 that, in the Solar System, a planet is a celestial body that:
- is in orbit around the Sun,
- has sufficient mass to assume hydrostatic equilibrium, and
- has "cleared the neighbourhood" around its orbit.
Bridgwater and Taunton College is a further education college based in the heart of Somerset, England, with main centres in Bridgwater, Taunton and Cannington. It educates approximately 3000 students between the ages of 16–18 in academic and vocational programmes in addition to several thousand part-time or mature students. The college was founded in 1973, although the history of its predecessor institutions dates to 1891.
The stability of the Solar System is a subject of much inquiry in astronomy. Though the planets have been stable when historically observed, and will be in the short term, their weak gravitational effects on one another can add up in unpredictable ways.
Discovery and exploration of the Solar System is observation, visitation, and increase in knowledge and understanding of Earth's "cosmic neighborhood". This includes the Sun, Earth and the Moon, the major planets Mercury, Venus, Mars, Jupiter, Saturn, Uranus, and Neptune, their satellites, as well as smaller bodies including comets, asteroids, and dust.
The Port of Bridgwater is a port, originally located in the town of Bridgwater, Somerset, England. Created under an 1845 Act of Parliament, it extends from Brean Down to Hinkley Point in Bridgwater Bay, and parts of the rivers Parrett, River Brue and River Axe. Although no ships now dock in the town, in 2001 103,613 (metric) tonnes of cargo were handled within the area of the Port Authority, most of which were stone products through the wharf at Dunball.
The Sciencenter's Sagan Planet Walk is a walkable scale model of the Solar System, located in Ithaca, New York. The model scales the entire Solar System—both planet size and distances between them—down to one five billionth of its actual size. The exhibition was originally created in 1997 in memory of Ithaca resident and Cornell Professor Carl Sagan.
The following outline is provided as an overview of and topical guide to the Solar System:
The Pajamäki Solar System Scale Model is a scale model of the Solar System built in Helsinki and partly in Espoo, Finland in 1992. Its scale is 1:1 000 000 000, i.e. one to one billion, so that 1 millimeter in the model corresponds to 1 000 kilometers in the actual Solar System. The coordinates given for the model are those for the Sun in Patterinmäki.
The Sun
Mercury
Venus
Earth (and Moon)
Mars
Jupiter
Saturn
Uranus
Neptune
Pluto
