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ANNULAR S LAR ECLIPSE AT THE CORE
The Sun: Our Star
The Sun: Our Star
TKapil Tripathi
he Sun, which binds all the planets of the solar system by its gravitational force, is a moderate-sized star. It is the nearest star from Earth and fulfils most of the requirements of light and heat needed to sustain life
on our planet.
The Sun emits a steady stream of charged particles called
solar wind that passes by Earth and the other planets creating what is known as ‘space weather’, which affects the Earth in many ways. At its worst, it can even damage satellites and cause electrical blackouts on Earth! To understand more about it, let us know more about the Sun.
Physical properties of the Sun
The Sun is a star and does not have a solid structure. Rather it is a hot, gaseous body with a core temperature of around 15,000,000°C and a surface temperature of about 5,600°C. Due to the extremely high temperature, no matter on Sun can exist in solid or liquid state. It can exist only as plasma – a gas of ions. The mass of the Sun is estimated to be about 2×1030 kg, which is about 3,33,000 times the mass of Earth.
Hydrogen and helium are the most abundant elements found on the Sun, making up about 98 per cent of its mass. The remaining amount is made up of oxygen, carbon, and other elements. The helium on the Sun was discovered in 1868,
almost 27 years before it was found on Earth (1895). Helium on the Sun was detected with the help of a spectroscope from Guntur (Andhra Pradesh) during the Total Solar Eclipse on 18 August 1868. The Sun is not stationary but rotates around its axis once in about 27 days. Being a gaseous body, different parts of the Sun revolve at different speeds. Its rotation period at the equator is around 25 days, which goes up to about 38 days near the poles.
The internal structure of the Sun
The temperature at the central part of the Sun is exceptionally high. At this high temperature, the nuclei of hydrogen start turning into helium nuclei through a process called thermonuclear reaction, which releases tremendous amounts of energy. In the process, around 42.50 lakh tons of hydrogen is converted into helium per second. This process is mainly responsible for producing energy in the Sun or any other star.
The core of the Sun is surrounded by six concentric spherical layers called radiative zone, convection zone, photosphere, chromosphere, transition region, and corona, respectively. From Earth we can see only the outer layers, namely photosphere, chromosphere, and corona. Sunlight comes mainly from the photosphere; the chromosphere and the solar corona are normally not visible. But during a total
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