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VIII SCIENCE- UNIVERSE AND SPACE SCIENCE- ANSWERS FOR TEXTBOOK EXERCISES
UNIVERSE AND SPACE SCIENCE
TEXTBOOK EXERCISES
I. Choose the best answer.
1. Which of the following is a celestial body?
a) Sun
b) Moon
c) Stars
d) All the above
Ans: d) All the above
2. Mangalyaan was sent to ________
a) Moon
b) Mars
c) Venus
d) Mercury
Ans: b) Mars
3. Chandrayaan - 1 was launched on
a) 22nd October 2008
b) 8th November 2008
c) 22nd July 2019
d) 22nd October 2019
Ans: a) 22nd October 2008
4. ________ is called as Red planet.
a) Mercury
b) Venus
c) Earth
d) Mars
Ans: d) Mars
5. Which of the following is the working principle of Rockets?
a) Newton’s first law
b) Newton’s second law
c) Newton’s third law
d) All the above
Ans: c) Newton’s third law
6. Cryogenic fuels are stored at
a) room temperature
b) low temperature
c) very low temperature
d) very high temperature
Ans: c) very low temperature
7. ________ was the first manned mission of NASA to go to the moon.
a) Apollo-5
b) Apollo-8
c) Apollo-10
d) Apollo-11
Ans: b) Apollo-8
II. Fill in the blanks.
1. The study about stars and planets are known as __________.
Ans: Astronomy
2. Our sun belongs to __________ Galaxy.
Ans: Milkyway
3. Mars revolves around the Sun once in __________ days.
Ans: 687
4. __________ is India’s first interplanetary mission.
Ans: Mars Orbiter Mission(MOM)
5. __________ was the first man to walk on the surface of the Moon.
Ans: Neil Armstrong
III. Say true or false. If false, correct the statement.
1. The Sun and the celestial bodies form Solar system.
Ans: True
2. Chandrayaan-1 was launched from Sriharikota.
Ans: True
3. Mars is the smallest planet in the Solar system.
Ans: False
Mercury is the smallest planet in the solar system.
4. PSLV and GSLV are India’s popular satellites.
Ans: PSLV and GSLV are India’s popular Satellite Launch Vehicles.
5. The propellant of a rocket is only in the form of solids.
Ans: False
The propellant of a rocket may be in the form of solid or liquid.
IV. Match the following.
Ans:
V. Answer briefly.
1. What are celestial objects?
The stars, the planets, the Moon and any other objects like asteroids and comets in the sky are called celestial objects.
2. Define galaxy.
A collection of billions of stars held together by mutual attraction is called a galaxy.
3. What are the objectives of Chandrayaan -1?
The following are the objectives of Chandrayaan – 1 mission.
⬛ To find the possibility of water on the Moon.
⬛ To find the elements of matter on the Moon.
⬛ To search for the existence of Helium-3.
⬛To make a 3-dimensional atlas of the Moon.
⬛ To study about the evolution of the solar system.
⬛ To find the possibility of water on the Moon.
4. List out the objectives of Mangalyaan.
The following are the objectives of Mangalyaan mission.
⬛ To develop the technology required for interplanetary missions.
⬛ To explore the surface of Mars
⬛ To study the constituents of the atmosphere of Mars.
⬛ To provide information about the future possibility of life and past existence of life on the planet.
5. What are Cryogenic Fuels?
In this type of fuel, the fuel or oxidizer or both are liquefied gases and they are stored at a very low temperature. These fuels do not need any ignition system. They react by mixing and start their own flame.
6. Name the Indians worked at NASA.
Kalpana Chawla, Sunitha Williams
VI. Answer in detail.
1. What are the achievements of Chandrayaan - 1?
Achievements of Chandrayaan-1
The following are the achievements of Chandrayaan-1 mission.
⬛ The discovery of the presence of water molecules in the lunar soil.
⬛ Chandrayaan-1 confirmed that the Moon was completely molten once.
⬛ Chandrayaan-1 has recorded images of the landing site of the US space-craft Apollo-15 and Apollo-11.
⬛ It has provided high-resolution spectral data on the mineralogy of the Moon.
⬛ The existence of aluminium, magnesium and silicon were picked up by the X-ray camera.
⬛ More than 40,000 images have been transmitted by the Chandrayaan-1 camera in 75 days.
⬛ The acquired images of peaks and craters show that the Moon mostly consists of craters.
⬛ Chandrayaan-1 beamed back its first images of the Earth in its entirety.
⬛ Chandrayaan-1 has discovered large caves on the lunar surface that can act as human shelter on the Moon.
2. Explain the parts of a rocket.
A rocket is a space vehicle with a very powerful engine designed to carry people or equipment beyond Earth and out into space. There are four major parts or systems in a rocket.
They are:
• Structural system
• Payload system
• Guidance system
• Propulsion system
Structural system (Frame):
The structural system is the frame that covers the rocket. It is made up of very strong but light weight materials like titanium or aluminum. Fins are attached to some rockets at the bottom of the frame to provide stability during the flight.
Payload system:
Payload is the object that the satellite is carrying into the orbit. Payload depends on the rocket’s mission. The rockets are modified to launch satellites with a wide range of missions like communications, weather monitoring, spying, planetary exploration, and as observatories.
Guidance system:
Guidance system guides the rocket in its path. It may include sensors, on-board computers, radars, and communication equipment.
Propulsion system:
It takes up most of the space in a rocket. It consists of fuel (propellant) tanks, pumps and a combustion chamber. There are two main types of propulsion systems. They are: liquid propulsion system and solid propulsion system.
3. Write a note on Apollo missions.
⬛ Apollo Missions are the most popular missions of NASA.
⬛ These missions made American Astronauts to land on the Moon.
⬛It consists of a total of 17 missions. Among them Apollo -8 and Apollo-11 are more remarkable.
⬛ Apollo-8 was the first manned mission to go to the Moon.
⬛ It orbited around the Moon and came back to the Earth. Apollo-11 was the first ‘Man Landing Mission’ to the moon.
⬛ It landed on the Moon on 20th July 1969.
⬛ Neil Armstrong was the first man to walk on the surface of the Moon.
VII. Higher Order Thinking Questions.
1. We always see one side of the Moon. Why?
The amount of time the moon takes to complete a revolution on its axis is the same it takes to circle our planet i.e. about 27 days. As a result, we always see one side of the moon.
