universe & solar system section 2 MCQ Questions & Answers Detailed Explanation

Answer: (b)

The twinkling of stars is due to the atmospheric refraction of stars. Stars twinkle because of turbulence in the atmosphere of the Earth. As the atmosphere churns, the light from the star is refracted in different directions. This causes the star’s image to change slightly in brightness and position, hence “twinkle.”

This is one of the reasons the Hubble telescope is so successful: in space, there is no atmosphere to make the stars twinkle, allowing a much better image to be obtained.

Answer: (c)

Answer: (a)

Answer: (a)

The colour of the star is an indication of its temperature. The glowing is caused by something called Black-Body radiation, which has to do with the heat energy trying to radiate away in more and more energetic wavelengths.

Red stars are relatively cool at only a few thousand degrees Celsius, white stars are hot at about ten thousand degrees, and blue stars are the hottest.

Answer: (d)

Answer: (c)

Earth is called the ‘Blue Planet’ due to the abundant water on its surface. This is because liquid water covers most of the surface of the planet.

The Earth has the right mass, chemical composition, and location can support liquid water.