Answer: The Universe is the vast space that contains millions of galaxies, stars, planets, satellites, asteroids, comets and meteors. It is infinite in size.
Question 2. What is the Milky Way Galaxy?
Answer: The Milky Way Galaxy (Akashganga) is the galaxy in which our solar system is located. It is spiral in shape and contains more than 100 billion stars.
Question 3. What is the Indian name of Pole Star?
Answer: The Indian name of the Pole Star is Dhruva Tara.
Question 4. What do you mean by Constellation?
Answer: A constellation is a group of stars connected by imaginary lines to form a particular shape in the sky.
Question 5. Define Planets.
Answer: Planets are heavenly bodies that revolve around the Sun and do not have light of their own.
Question 6. Why is the Earth called the Blue Planet?
Answer: Earth is called the Blue Planet because about two-thirds of its surface is covered with water, which makes it appear blue from space.
Question 7. Define Comets and Meteors.
Answer: Comets are heavenly bodies made of dust and frozen ice with a bright head and long tail. Meteors are small fragments of asteroids that enter the Earth’s atmosphere and burn, appearing as shooting stars.
[B] Fill in the blanks with suitable words.
Question 1: The diameter of the Sun is about........... times of the diameter of the Earth.
Answer: 109
Question 2: The Sun is made up of ........ and ................
Answer: Hydrogen and Helium
Question 3: The ........... are the tiny fragments of the planets.
Answer: Asteroids
Question 4. Halley’s Comet appears in the sky after every ........... years.
Answer: 76
Question 5: ......... was excluded from the list of the planets.
Answer: Pluto
[C] Write whether the following statements are true or false.
Question 1. Earth completes one revolution around the Sun in 365 days.
Answer: True
Question 2: Mercury, Venus, Earth, Mars are made up of liquid materials.
Answer: False
Question 3: The surface temperature of the Sun is about 15000000°C while at the centre it is 6000°C.
Answer: False
Question 4: Ursa Major is an example of a constellation.
Answer: True
Question 5: There are 8 planets in the solar system.
Answer: True
[d] Write down the answers in brief.
Question 1. Discuss briefly about the Solar System.
Answer: The Solar System consists of the Sun at the centre and eight planets—Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune. These planets revolve around the Sun due to its gravitational force. The solar system also includes satellites, asteroids and comets.
Question 2: Write a short note on the Big Bang Theory and the Phases of the Moon.
Answer: Big Bang Theory: It explains the origin of the universe. According to this theory, the universe was once in a highly compressed state and a huge explosion (Big Bang) caused matter to spread in space and form galaxies, stars and planets.
Phases of the Moon: The Moon changes its shape as seen from Earth due to its movement around Earth. The main phases are New Moon, Crescent Moon, Full Moon, and then it decreases again. The complete cycle takes about 29½ days.
Question 3: Write a short note on the Earth.
Answer: Earth is the third planet from the Sun and the fifth largest planet in the solar system. It is called the Blue Planet because most of its surface is covered with water. Life exists on Earth because of water, suitable atmosphere and moderate temperature. Earth completes one rotation in 24 hours and one revolution around the Sun in 365 days.
Question 4: Write a short note on Meteors.
Answer: Meteors are small fragments of asteroids that enter the Earth’s atmosphere. When they burn due to friction, they appear as bright streaks of light in the sky called shooting stars. If a large meteor reaches the Earth’s surface, it is called a meteorite.
