• The Sun:


Introduction:
The sun is the star, which is nearest to the earth. It is the center of our solar system. All planets revolve round it.

Following are the main features of the Sun.
Composition of the Sun:
The Sun composed of: -
Hydrogen 90%
Helium 8%
Other elements 2%

Temperature of the Sun:
The Sun is a hot gaseous mass whose surface temperature is very gigh. The temperature of the Sun is divided into the following two types:

Photosphere: - The surface temperature of the Sun is called as the photosphere, that is 6000o C.

 Chromosphere: - The interior temperature of the Sun is called Chromosphere, that is about 15 million degree C.

Characteristics of the Sun:
The Mass of the sun is 2*1030 tons.
The diameter of the Sun is 1.4 million kms.
Its mean distance from the earth is 149 million kms.
The average density of the sun is 1.4 gm/cc.
The main source of energy in the sun is Hydrogen, which is coveted into Helium by the process of nuclear fusion.
The Sun has 27 days solar rotation period and 11-years sunspot cycle.
The Sun is classified as a ‘yellow dwarf’ star of spectral types G2V.
The minimum distance between sun & the Earth is known as perihelion, which is 147,098,200 kms & the maximum distance between the sun, & the Earth is called aphelion, that is 152,097,900 kms.

Some Features of the Sun:

Sun Spots:
Sun spots are a number of dark patches on the surface of the sun. They are seen through a telescope with colored glass. They are funnel-shaped vortex through which gaseous matter streams spiral upwards and outwards. The sun spots vary greatly both in size and duration. Some of them disappear in the course of a few days, others survive for one or two revolutions of the sun. Large spots may be more than 100,000 miles in diameter.


Solar Wind:
Solar wind is composed of protons and electron, which are streams of electricially charged particles, which are emitted by the Sun.