Astronomy and Celestial Phenomena

The sentence refers to an accepted fact. The tense of the sentence is Simple Present. The subject of the sentence is third person plural. Here the first form of verb will be used. Hence 'revolve' is the correct option.

The tense of the sentence is Simple Present as it refers an accepted fact. The subject of the sentence is third person singular. Here first form of the verb with 's' is to be used. Hence 'revolves' is the correct option.

The Earth's axial tilt (approximately 23.5 degrees) is the primary reason for seasons. Without this tilt, the amount and intensity of sunlight received at different latitudes would remain constant throughout the year, resulting in no seasonal changes. Option A is incorrect because seasons would not exist at all, let alone have the same duration. Options C and D are incorrect because there would be no distinct summer or winter periods.

The change of seasons is caused by Earth's revolution around the sun combined with its axial tilt of approximately 23.5 degrees. As Earth orbits the sun, different hemispheres receive varying amounts of sunlight throughout the year, creating seasonal patterns. Day and night are caused by Earth's rotation on its axis.

This is due to atmospheric refraction - light bends when passing through layers of air with different densities (which vary with temperature and altitude). This bending makes the moon appear slightly higher than its actual geometric position. The same principle explains why the sun is visible before it actually rises and after it sets.

The Moon has no atmosphere because its escape velocity (2.38 km/s) is much lower than the root mean square velocity of gas molecules at lunar surface temperatures. Light gas molecules (like hydrogen and helium) easily exceed escape velocity and escape into space over geological time. Higher mass molecules might be retained, but the Moon lacks significant sources for these gases.

Aurora borealis (Northern Lights) is a natural light display caused by charged particles from the solar wind interacting with Earth's magnetic field and atmosphere near the polar regions. The southern hemisphere equivalent is aurora australis. The lights appear as curtains, rays, or spirals of colored light.

The Moon has an extremely thin atmosphere (exosphere) that is insufficient to scatter sunlight in the way Earth's atmosphere does. On Earth, Rayleigh scattering in our atmosphere makes the sky appear blue during the day. Without a significant atmosphere, the lunar sky appears black even during the daytime, with the Sun appearing as a bright disc against the dark background.

Perigee is the point in a satellite's orbit where it is closest to Earth. The opposite term is apogee (farthest point). These terms are fundamental in orbital mechanics and satellite communication planning, as the varying Earth-satellite distance affects signal strength and coverage.

Diamond Harbour in Kolkata was used as a viewing station for the Total Solar Eclipse of 1995 (and other eclipses). The location's positioning made it suitable for astronomical observations, thus the association.

The line 'Rainbows are often seen when the sun comes out after or during a rainstorm' suggests the answer.

The line '...rainbows sometimes appear as white arcs at night... called moonbows' suggests the answer. 

Option (4) is the correct answer as the passage gives us the basic knowledge of types of rainbows and what causes them.