A detailed examination of solar physics and geography. Key focus areas include the internal structure of the Sun, solar activity cycles (sunspots), solar flares, coronal mass ejections (CMEs), and their geomagnetic impacts on Earth's ionosphere and satellites.
Time taken by the Sun to revolve around the centre of our galaxy is –
Correct Answer:
(C) 25 crores years
Sun is one of the stars of our galaxy (Milky Way). Every star of the galaxy revolves around the galactic centre and the time taken by a star in revolving around this centre depends upon the distance between the galactic centre and the star. Sun is relatively far from the centre, so it takes more time to revolve around. Sun is at a 7.94 KPC or 25.896 thousand light years away from the centre and with a speed of 220 Km/sec, it takes 22.5 to 25 crore years, to revolve around the centre of the Milky Way galaxy. This period is called ‘Cosmic Year or Galactic Year’.
Ques: 2
Who first propounded that the Sun is the centre of our Solar system and the earth revolves around it?
Correct Answer:
(D)
Copernicus
Nicolaus Copernicus was an astronomer, scientist, mathematician of Poland. In 1514, Copernicus propounded the Heliocentric Theory of the solar system in his work 'Commentariolus' (Little commentary). Notably, Indian astronomers Varahamihira propounded the same theory around a thousand years before Copernicus in the sixth century. He mentioned that the moon revolves around the earth and the earth rotate around the sun.
Ques: 3
Sun's halo is produced by the refraction of light in –
Correct Answer:
(C) Ice crystals in Cirrus clouds
The Sun’s halo is a circle which appears around the sun. Whenever Sun rays pass through the ice crystal present at the upper level of cirrus clouds, sun's halo becomes visible due to the refraction of rays.
Ques: 4
Size of the Sun is how many times bigger than that of the earth ?
Correct Answer:
(C) 109 times
According to NASA, the size of the sun is 109.2 times the diameter of the earth. The mean radius of the sun is 695508 km while the equatorial radius of the earth is 6378 km.
Ques: 5
Consider the following statements about Sun:
The sun is not a solid object but rather a big ball.
The sun is mostly made of Hydrogen and Helium.
Which of the statements given above is/are correct?
Correct Answer:
(C) Both 1 and 2
The sun is not a solid object, but rather a huge, hot ball of gas, primarily hydrogen and helium, held together by gravity. It's a star, and its energy is produced through nuclear fusion, which converts hydrogen into helium, releasing tremendous amounts of energy in the form of light and heat.