universe & solar system section 9 MCQ Questions & Answers Detailed Explanation

Answer: (c)

Answer: (c)

The group of stars arranged in a definite pattern is called a constellation. In modern astronomy, a constellation is an internationally defined area of the celestial sphere.

These areas are grouped around asterisms, which are patterns formed by prominent stars within apparent proximity to one another on Earth’s night sky.

Answer: (a)

Pluto, formal designation 134340 Pluto, is the second-most-massive known dwarf planet in the Solar System (after Eris) and the tenth-most-massive body observed directly orbiting the Sun.

Originally classified as the ninth planet from the Sun, Pluto was recategorized as a dwarf planet and plutoid owing to the discovery that it is only one of several large bodies within the Kuiper belt.

Like other members of the Kuiper belt, Pluto is composed primarily of rock and ice and is relatively small, approximately one-sixth the mass of the Earth’s Moon and one-third its volume. It has an eccentric and highly inclined orbit that takes it from 30 to 49 AU (4.4–7.4 billion km) from the Sun. This causes Pluto to periodically come closer to the Sun than Neptune. Pluto gets as close as 4.44 billion km.

But its orbit is so elliptical that it gets out to a distance of 7.38 billion km. In fact, there are times in Pluto’s orbit when Neptune passes it. Then Neptune really is the farthest planet from the Sun.

Answer: (b)

The approximate diameter of Earth is 12800 km. The rotation of the planet has slightly flattened it out, so it has a larger diameter at the equator than at the poles.

The equatorial diameter of Earth is 12,756 km, its polar diameter is 12,713 km, and its average diameter, which is referred to in common usage, is 12,742 km or 7,926 miles.

Answer: (d)

Latitude is distance North or south of the equator. It may also be defined as an angle which ranges from 0° at the equator to 90° at the poles.

Answer: (c)

The inexhaustible source of energy of the stars is due to the conversion of Hydrogen to Helium. In the interior of a star, the particles move rapidly in every direction because of the high temperatures present.

Every so often a proton moves close enough to a nucleus to be captured, and a nuclear reaction takes place. Only protons of extremely high energy (many times the average energy in a star such as the Sun) are capable of producing nuclear events of this kind. The minimum temperature required for fusion is roughly 10 million K.

Since the energies of protons are proportional to temperature, the rate of energy production rises steeply as temperature increases.