What is Solar System?Our Solar System is made up of nineplanets, their moons, and our sun. Theplanets and their moons revolvearound, or orbit the sun.The orbits are not round. They areelliptical ( E-lip-tih-cul). Elliptical meansegg-shaped.
The first four planets are called the innerplanets. They are closest to the sun. Theirnames are Mercury, Venus, Earth andMars. These planets are made mostly ofrock. The next five planets are called the outer planets. Saturn, Jupiter, Uranus and Neptune are called gas giants because they are made mostly of gases. The last planet is called Pluto. It is coated with ice.
MERCURY -Mercury is the innermost and smallest planet in the Solar System.[a] It orbits the Sun once every 87.969 Earth days, completing three rotations about its axis for every two orbits. Mercurys orbit has the highest eccentricity of all the Solar System planets, and Mercury has the smallest axial tiltVENUS-Venus is the second planet from the Sun, orbiting itevery 224.7 Earth days. The planet is named afterVenus, the Roman goddess of love and beauty. Afterthe Moon, it is the brightest natural object in the nightsky, reaching an apparent magnitude of −4.6, brightenough to cast shadows.
EARTH -Earth (or the Earth) is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar Systems four terrestrial planets. It is sometimes referred to as the world, the Blue Planet, or by its Latin name, Terra.[note 6]MARS-Mars is named after the ancient Roman god of war, asbefitting the red planets bloody color. The Romanscopied the ancient Greeks, who named the fourthplanet from the sun after their god of war, Ares. Othercivilizations also typically gave the planet names basedon its color
SATURN -Saturn is the sixth planet from the Sun and the second largest planet in the Solar System, after Jupiter. Named after the Roman god Saturn, its astronomical symbol (♄) represents the gods sickle. Saturn is a gas giant with an average radius about nine times that of Earth.[ - Saturn has a ring system that consists of nine continuous main rings and three discontinuous arcs, composed mostly of ice particles with a smaller amount of rocky debris and dustJUPITER-Jupiter, the most massive planet in our solarsystem -- with dozens of moons and anenormous magnetic field -- forms a kind ofminiature solar system. Jupiter does resemblea star in composition, but it did not grow bigenough to ignite. The planets swirling cloudstripes are punctuated by massive stormssuch as the Great Red Spot, which has ragedfor hundreds of years.
URANUS -Uranus is the seventh planet from the Sun and is the third largest in the solar system. It was discovered by William Herschel in 1781. It has an equatorial diameter of 51,800 kilometers (32,190 miles) and orbits the Sun once every 84.01 Earth years. It has a mean distance from the Sun of 2.87 billion kilometers (1.78 billion miles). It rotates about its axis once every 17 hours 14 minutes. Uranus has at least 22 moons. The two largest moons, Titania and Oberon, were discovered by William Herschel in 1787.NEPTUNE-Neptune is the outermost planet of the gas giants. It has anequatorial diameter of 49,500 kilometers (30,760 miles). IfNeptune were hollow, it could contain nearly 60 Earths.Neptune orbits the Sun every 165 years. It has eight moons,six of which were found by Voyager. A day on Neptune is 16hours and 6.7 minutes. Neptune was discovered onSeptember 23, 1846 by Johann Gottfried Galle, of the BerlinObservatory, and Louis dArrest, an astronomy student,through mathematical predictions made by Urbain JeanJoseph Le Verrier.
PLUTO -Pluto is a dwarf planet (or plutoid) that usually orbits past the orbit of Neptune. It was classified as a dwarf planet in 2006; before that it was considered to be a planet, the smallest planet in our solar system. There are many other dwarf planets in our Solar System. Pluto is smaller than a lot of the other planets moons, including our moon. Pluto has not been visited by spacecraft yet; we only have blurry pictures of its surface; even the Hubble Space Telescope orbiting the Earth can only get grainy photos because Pluto is so far from us. In 2015, a spacecraft called New Horizons (launched by NASA in 2006) will visit Pluto.Pluto is about 1,413 miles (2274 km) in diameter.This is about 1/5 the diameter of the Earth.Pluto is smaller than the 8 planets in our SolarSystem.