Sun – Physical Geography (UPSC)

• The Sun can be considered the heart of our solar system. It is the largest object in the solar system, making up 99.8% of its mass.
• The Sun’s surface temperature is about 6000°C, increasing to approximately 20 million °C in its interior.
• Its surface is composed of fiery gases that leap in whirls of glowing flames, resembling volcanic eruptions. The Sun has 300,000 times the mass of Earth.
• It is the only star in our solar system and serves as its powerhouse.
• The Sun is composed of 73% Hydrogen, 25% Helium, and other elements.
• Light from the Sun takes an average of 8 minutes and 20 seconds to reach Earth, while light from the Moon takes only about a second. The Sun consists of several distinct regions:

Corona:

• The outermost layer of the Sun, extending thousands of kilometers above the photosphere.
• Its temperature exceeds 1,000,000 Kelvin, significantly higher than the solar disc’s temperature of around 6000K.
• The reason for this extreme heating of the outer layer remains an unanswered question in solar physics.

Sunspots:

• These dark regions on the Sun’s visible surface are areas of intense magnetic activity, often leading to solar flares.

Heliosphere:

• The Sun generates electric currents that create a complex magnetic field extending into space as the interplanetary magnetic field.
• The heliosphere refers to the volume of space influenced by the Sun’s magnetic field.

Solar Wind:

• The Sun emits storms of electrically charged gas, known as the solar wind, in all directions.
• The Sun’s magnetic field, carried by the solar wind, forms a spiral shape called the Parker spiral due to the Sun’s rotation.