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Tuesday 6 March 2018

The Solar System

The Solar System comprises the Sun and the planets, their moons, asteroids, comets and other objects that orbit it.

There are eight major planets in the Solar System. From closest to farthest from the Sun, they are: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune.

The world's largest scale model of the Solar system exists in Sweden. The Sun is a large spherical arena in Stockholm with 110m in diameter. 300km north of it is Pluto, a small sphere of 12 cm in diameter constructed next to a lake believed to have been created by a meteorite impact.

The Solar System can never come into perfect alignment. The last time the eight major planets  appeared even in the same part of the sky was over 1,000 years ago, in the year AD 949, and they won’t manage it again until May 6, 2492.

The Sun contains 99.9 percent of the Solar System's mass.

Below is a representative image of the Solar System with sizes, but not distances, to scale

By WP - Planets2008.jpg,

The Solar System also contains asteroids, which are mostly between Mars and Jupiter.

The asteroid Oumuamua is the first known interstellar object to pass through the Solar System. It was discovered on a highly eccentric hyperbolic trajectory by Robert Weryk on October 19, 2017, 40 days after turning around the Sun. The first observations were made by the Pan-STARRS telescope when the object was 30,000,000 km; (19,000,000 mi) from Earth.

'Oumuamua racing toward the outskirts of our solar system

Beyond Neptune's orbit lie the Kuiper belt and scattered disc, which are populations of trans-Neptunian objects composed mostly of ices, and beyond them a newly discovered population of sednoids. Within these populations are several dozen to possibly tens of thousands dwarf planets.

Identified dwarf planets include the asteroid Ceres and the trans-Neptunian objects Pluto and Eris.

Eris, discovered in 2005, is approximately three times further away from the Sun as Pluto. Eris itself also is known to have a moon, Dysnomia. It was partially the discovery of Eris that set aflame the argument over what should be considered a planet or not.  Below is an artist's impression of the dwarf planet Eris and its large moon Dysnomia.

By ESO/L. Calçada and Nick Risinger (skysurvey.org) 

Before Eris was called Eris, the discoverers called it Xena, after Xena: Warrior Princess.

V774104 is a trans-Neptunian object (TNO) roughly half the size of Pluto and currently about 103 AU from the Sun, a distance of 15.4 billion kilometers (9.6 billion miles). As of the announcement of the discovery in November 2015, it is the most distant observed natural object in the Solar System.

There are also comets, centaurs (planetoids), and interplanetary dust clouds, which consists of cosmic dust that pervades the space between planets in the Solar System.

Our solar system—with the sun, the planets and their moons, and the billion of asteroids and comets—fills less than a trillionth of our universe.

The Solar System is located in the Orion Arm, 26,000 light-years from the center of the Milky Way.

Our solar system is currently traveling through an interstellar cloud which is 30 light years long. It is thought to have entered the region at some point between 44,000 and 150,000 years ago and is expected to remain within it for another 10,000 to 20,000 years. The cloud is about the same temperature as the surface of the Sun. However, its specific heat capacity is very low because it is not very dense, with 0.3 atoms per cubic centimetre (4.9/cu in)

Many other systems like the Solar System have been found. Each of the billions of stars in the Milky Way galaxy might have a planetary system.

The coldest place in our solar system is not Pluto, it's Triton, one of Neptune's moons. Its surface temperature is at least 35.6 K (−237.6 °C), while Pluto's average equilibrium temperature is 44 K (−229 °C).

Voyager 2 photomosaic of Triton[caption 1]

From a distance, Earth would be the brightest of the planets. This is because sunlight is reflected off the planet's water.

If you lined all the planets in the Solar System side by side they would fit almost perfectly between the Earth and the Moon with only about 5,000 miles to spare

Earth is the only planet in the Solar System not named after a Roman or Greek god.

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