Astronomy and Celestial Phenomena

Rainbows occur when sunlight is refracted, reflected, and dispersed through water droplets in the atmosphere. This phenomenon is most visible when the sun is relatively low in the sky - typically 40 degrees or less above the horizon. When the sun is higher, the rainbow angle becomes too shallow to be visible from the ground, or it may be below the horizon.

Rotation means spinning on an axis. Earth rotates west to east on its own axis once every 24 hours, creating day and night. Option A describes revolution (orbiting the sun), not rotation. Option B is incorrect - Earth doesn't orbit the moon.

The correct answer is C. Auroras are natural light displays that are 'observed' (watched/seen) at night, and they occur 'only' in polar regions (Arctic and Antarctic). This combination captures both the visual nature of auroras and their geographical restriction. Options like 'watch, upward' or 'found, most' don't capture the precise meaning - auroras aren't typically described with 'upward', and 'most' in polar regions would suggest they also occur elsewhere, which is incorrect.

The photosphere is the visible surface of the sun - a layer about 500 km thick where the sun's gases become thin enough for light to escape. It appears yellow and has a temperature of about 5,500°C. The corona (outer atmosphere) is only visible during eclipses, while ionosphere and stratosphere relate to Earth's atmosphere.

Moon is a natural satellite (orbiting body), and Earth is a planet (primary body that orbits the sun). The analogy follows the pattern 'satellite: primary body'. So just as Moon relates to being a satellite, Earth relates to being a planet. Air, Sun, and Sea don't fit the classification pattern.

The correct answer is black. Unlike Earth, the Moon has no atmosphere to scatter sunlight. On Earth, Rayleigh scattering makes the sky appear blue. On the Moon, even during daytime, the sky appears black because there's no air to scatter light.

This is the correct option. Photonasty is response to light.

A shadow is shortest when the Sun is directly overhead, which happens at noon. At this time, the sun's rays are most nearly vertical, casting the shortest shadow. In the morning and evening, when the Sun is lower in the sky, shadows are much longer.

Yes, it is the correct. The Moon does not have light of its own, it reflects sunlight and is visible. The rest are all luminous objects, hence the Mmoon is the correct answer.

Yes, a shadow cast by the Earth on the Moon is a lunar eclipse. Conversely, a shadow cast by the Moon on the Earth is a solar eclipse.

Yes, it is correct. Luminosity is the measure of the Sun's apparent brightness and distance. The light produced by it allows us to see objects around us.

Yes, it is correct. This shaded region surrounding the dark central portion of a sunspot (umbra) is the penumbra. A Penumbra is not as dark as the umbra region. It is light shaded part surrounding the dark shadow.

The indefinite article 'a' is correct because 'star' is used in a generic sense here - the sun is one of many stars in the universe. We use 'a' (not 'an') because 'star' begins with a consonant sound, and we don't use 'the' because we're not referring to a unique, specific star.

A solar eclipse happens when the Moon passes between the Sun and Earth, casting a shadow on Earth and either partially or fully blocking the Sun's light. This phenomenon can only occur during the New Moon phase when the three bodies are aligned.

Yes, it is correct. In polar region, the sun does not set for about six months and it does not appear for another six months of the year.