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Solar system

Our solar system consists of the Sun, and everything bound to it by gravity — the planets Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune, dwarf planets such as Pluto, dozens of moons and millions of asteroids, comets and meteoroids.

Beyond our own solar system, there are more planets than stars in night sky. So far, we have discovered thousands of planetary systems orbiting other stars in the Milky Way, with more planets being found all the time.

Most of the hundreds of billions of stars in our galaxy are thought to have planets of their own, and the Milky Way is but one of perhaps 100 billion galaxies in the universe.

Our solar system extends much farther than the eight planets that orbit the Sun. The solar system also includes the Kuiper Belt that lies past Neptune's orbit. This is a sparsely occupied ring of icy bodies, almost all smaller than the most popular Kuiper Belt Object, dwarf planet Pluto.

The Solar System formed 4.6 billion years ago from the gravitational collapse of a giant interstellar molecular cloud. The vast majority of the system's mass is in the Sun, with the majority of the remaining mass contained in Jupiter.

The four smaller inner planets, Mercury, Venus, Earth and Mars, are terrestrial planets, being primarily composed of rock and metal. The four outer planets are giant planets, being substantially more massive than the terrestrials.

The two largest, Jupiter and Saturn, are gas giants, being composed mainly of hydrogen and helium; the two outermost planets, Uranus and Neptune, are ice giants, being composed mostly of substances with relatively high melting points compared with hydrogen and helium, called volatiles, such as water, ammonia and methane.

All eight planets have almost circular orbits that lie within a nearly flat disc called the ecliptic.

The solar wind, a stream of charged particles flowing outwards from the Sun, creates a bubble-like region in the interstellar medium known as the heliosphere.

The heliopause is the point at which pressure from the solar wind is equal to the opposing pressure of the interstellar medium; it extends out to the edge of the scattered disc.

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

The statistics of the sun and the planets are given below :

Age : About 5 Billion years

Distance : 149.8 Million Kms

Diameter : 1,38,400 Kms.

Photosphere temperature : 5,770 K

Core temperature : 150,000,000 K

Absolute visual magnitude : 4.75

Rotation (as seen from the earth at the equator) : 25.38 days

Rotation (near the poles) : 33 days

The sun consists of 71% of Hydrogen, 26.5% Helium and 2.5% of other elements.

The rays of the Sun take about 8 minutes to reach the earth.

Last updated on: 01/10/2019


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