Dear Readers,

Current affairs is an important component of several competitive exams such as the UPSC Civil Services Examination, SSC-CGL, Bank PO & PSU entrance tests, etc. Therefore, understanding the terms/concepts/events that make news is critical for aspirants. We at PaGaLGuY bring you this series of articles explaining some of these important concepts/events. In this article we are discussing the Sun and our Solar System. 

Our Solar System has the Sun and eight planets that revolve around the Sun in elliptical orbits. 

Few of these planets have their own satellites orbiting around them. The following bodies are also part of our Solar System.

Asteroids

Comets

Meteors

Plutoids

Intersteller dust and cloud 

Sun: 

a) Sun is the only star in our Solar System as it has its own source of light and energy.

b) Mass of the Sun accounts to 99.86% of our Solar System.

c) Its average distance from the Earth is around 149,600,000 km. Sunlight takes about 8 minutes 17 seconds to travel the average distance from the surface of the Sun to the Earth.

d) Sun’s energy is produced by controlled nuclear fusion in its core through a series of processes called the p-p (proton-proton) chain. This process converts Hydrogen into Helium.

Composition : 

Hydrogen       74.9%

Helium            23.8%

Metals            1.3%

Structure of Sun :

The structure of the Sun can be divided into 5 different layers that are as follows:

a) Core : 

The core of the Sun has the highest temperature and pressure among all layers. The temperature of the core is around 15 million degree Celsius.

The core is in an ionised state called plasma, which is also the fourth state of matter (after solids, liquids and gases).

The solar energy is produced in the core by controlled nuclear fusion process.

The high temperature in the core helps in removing the electrons from hydrogen atoms and in creating numerous electrons and protons for nuclear fusion. 

The Sun’s radiative zone is the section of the solar interior between the innermost core and the outer convective zone. In the radiative zone, energy generated by nuclear fusion in the core moves outward as electromagnetic radiation.

b) Convective zone :

In this zone the density of plasma is low.

This zone transports hot and light density fluids from the core region of high energy & temperature to the outer region of low energy & temperature.

c) Photosphere :

This the first visible layer of the Sun.

The temperature here is around 6000 degree Kelvin (5370 degree Celsius).

The solar spots are formed on this layer.  The temperature of a solar spot is around 4500 degrees.

(Solar spot : They are temporary dark spots formed when the magnetic field bursts through the surface. It can slow down the flow of energy from the inside of the Sun – that’s what makes the sun spots cooler & darker than the surrounding photosphere.)

d) Chromosphere : 

Chromosphere literally mean as ‘sphere of colour’. This layer is dominated by emission lines.

e) Corona :

This is the outer layer of the Sun. High temperature in this region gives it an unusual spectral feature of a highly ionised ion.

Both chromosphere & corona are clearly visible only during formation of Diamond Ring during Solar eclipse.