Keywords To Remember
Astronomy & Space Vocabulary
Keyword | Definition |
Universe | The totality of space, time, matter, and energy, including all galaxies, stars, and planets. |
Celestial Body | Any natural object in space, such as a star, planet, moon, or asteroid. |
Galaxy | A massive system of stars, gas, dust, and dark matter held together by gravity. |
Milky Way | The spiral galaxy in which our solar system is located. |
Orion Arm | A minor spiral arm of the Milky Way Galaxy where our solar system is found. |
Solar System | The Sun and all the celestial bodies that orbit around it, including planets, moons, asteroids, and comets. |
Star | A giant ball of hot, glowing gases that generates light and heat through nuclear fusion. |
Light Year | The distance that light travels in one year, about 9.46 trillion kilometers (5.88 trillion miles). |
Constellation | A group of stars forming a recognizable pattern in the sky. |
Pole Star (Dhruv Tara) | A bright star (Polaris) that lies nearly in a direct line with the Earth’s rotational axis above the North Pole. |
Planets & Earth Vocabulary
Keyword | Definition |
Planet | A celestial body that orbits a star, is spherical, and has cleared its orbit of other debris. |
Terrestrial Planet | A rocky planet with a solid surface, such as Mercury, Venus, Earth, or Mars. |
Gas Giant | A large planet composed mainly of hydrogen and helium, like Jupiter or Saturn. |
Ice Giant | A planet with a thick atmosphere and icy interior, like Uranus or Neptune. |
Orbit | The curved path of a celestial body around a star, planet, or moon. |
Rotation | The spinning of a celestial body on its axis. |
Revolution | The movement of a celestial body around another object, like the Earth around the Sun. |
Satellite | A natural or artificial body that revolves around a planet; e.g., the Moon. |
The Moon & Phenomena Vocabulary
Keyword | Definition |
Moon Phase | The different appearances of the Moon from Earth as it orbits our planet. |
New Moon | The phase when the Moon is not visible from Earth. |
Full Moon | The phase when the entire face of the Moon is illuminated and visible. |
Crescent Moon | A moon phase in which only a small curved edge is visible. |
Crater | A bowl-shaped cavity caused by a meteorite impact or volcanic activity. |
Other Celestial Objects Vocabulary
Keyword | Definition |
Asteroid | A small rocky body orbiting the Sun, mostly found between Mars and Jupiter. |
Asteroid Belt | The region between Mars and Jupiter where most asteroids are located. |
Meteoroid | A small piece of rock or debris in space. |
Meteor | A meteoroid that burns up upon entering Earth’s atmosphere (shooting star). |
Meteorite | A meteoroid that survives its passage through Earth’s atmosphere and lands on Earth. |
Comet | A celestial object made of ice, dust, and gas with a glowing head and long tail, which appears when near the Sun. |
Nebula | A large cloud of gas and dust in space, often a birthplace of stars and planets. |
General Scientific Vocabulary
Keyword | Definition |
Self-luminous | Able to emit its own light. |
Gravitational Force | A natural force that pulls objects toward each other. |
Spherical | Shaped like a sphere (ball), round in three dimensions. |
Atmosphere | The layer of gases surrounding a planet. |
Volcanic Activity | The eruption or movement of molten rock on a planet’s surface. |
Something To Know
A. Tick (✔ ) the correct option.
- What do we call a huge cluster of billions of stars?
(a) asteroids
(b) meteors
(c) galaxy
(d) universe
Answer – (c) galaxy
- Which one of the following is the hottest planet?
(a) Mercury
(b) Venus
(c) Mars
(d) Jupiter
Answer – (b) Venus
- Which is the most distant planet from the Sun?
(a) Uranus
(c) Saturn
(b) Neptune
(d) Jupiter
Answer – (b) Neptune
- The planet which does not have any satellite is ̶
(a) Venus
(b) Mars
(c) Neptune
(d) Earth
Answer – (a) Venus
- Which planet has two satellites?
(a) Mercury
(b) Venus
(c) Earth
(d) Mars
Answer – (d) Mars
B. Fill in the blanks.
- The vast limitless space which includes all celestial bodies is called ________________.
Answer – Universe
- The distance between celestial bodies is measured in a unit called ________________ .
Answer – light year.
- ________________ always indicates the north direction.
Answer – Pole Star
- All the planets of our solar system revolve round the Sun in their fixed paths called ________________ .
Answer – orbits
- ________________ is the third nearest planet to the Sun.
Answer – Earth
C. Match the following:
- Great Bear a. Nebula
- Head of solar system b. Mars
- A giant cloud of gases and dust c. Sun
- Shape of the earth d. Constellation
- Red Planet e. Spherical
Answer –
A | B | Answer |
1. Great Bear | d. Constellation | 1 → d |
2. Head of solar system | c. Sun | 2 → c |
3. A giant cloud of gases and dust | a. Nebula | 3 → a |
4. Shape of the earth | e. Spherical | 4 → e |
5. Red Planet | b. Mars | 5 → b |
D. Answer the following questions in brief.
- What are celestial bodies?
Answer – Celestial bodies are natural objects in the sky such as the sun, moon, planets, and stars.
- Why do stars look very small in the sky?
Answer – Stars look small because they are very far away from the earth.
- What is ‘Saptarishi Mandal’?
Answer – It is a group of seven stars, part of the Ursa Major constellation, visible in the northern sky.
- Name the planets which are gaseous bodies.
Answer – Jupiter, Saturn, Uranus, and Neptune are gaseous planets.
- Which planet is the closest to Neptune?
Answer – Uranus is the closest planet to Neptune.
E. Answer the following questions.
- Describe the formation of solar system.
Answer – The solar system formed around 4.6 billion years ago from a giant cloud of gas and dust called the Nebula. The cloud started rotating, and under gravity, it formed a central mass (the Sun) and smaller clumps that became the planets.
- State three features which make the earth a unique planet.
Answer – It has life-supporting water and air.
It receives moderate heat and light from the Sun.
It has a protective atmosphere and suitable temperature for life.
- Mention three main characteristics of a satellite.
Answer – It revolves around a planet.
It does not produce its own light.
It reflects sunlight and may be natural or man-made.
- Give a brief description on the Phases of Moon with the help of a diagram.
Answer – The moon reflects sunlight. As it revolves around the Earth, the visible portion of the illuminated side changes:
New Moon: No moon visible
Crescent: Thin moon
Half Moon: Half of the moon visible
Full Moon: Entire face visible
After full moon, it again reduces to new moon.
(You can draw a circular sequence showing the 8 phases: New Moon → Waxing Crescent → First Quarter → Waxing Gibbous → Full Moon → Waning Gibbous → Last Quarter → Waning Crescent → New Moon)
- Write a short note on the other celestial bodies ( asteroids, meteoroids and comets) in the solar system.
Answer – Asteroids are rocky objects mostly found between Mars and Jupiter in the Asteroid Belt.
Meteoroids are small rock pieces in space. When they enter Earth’s atmosphere and burn up, they are called meteors or shooting stars.
Comets are icy objects with glowing heads and long tails, like Halley’s Comet, seen periodically.
Value Based Question
Indian Space Research Organisation (ISRO) was established in 1969. It was the same year when humans set foot on the moon for the first time. ISRO launched Chandrayaan-1 on October 22, 2008 from Sriharikota. It showed India’s ability to do meaningful science at low cost, its leadership in a cooperative space venture and the capacity to develop essential technology within stipulated time. With this success, India became the fifth country to put a spacecraft into an orbit around the moon after the United States, Soviet Russia, Japan and China.
- What is meant by ‘meaningful science’?
Answer – Meaningful science refers to scientific activities that solve real problems and benefit society.
- Mention any two inventions to distinguish between ‘science’ and ‘meaningful science’.
Answer – Science: Discovery of electricity
Meaningful science: Use of electricity to power homes and hospitals
- Explain the values and life skills which helped India to attain success in space.
Answer – Determination and hard work
Innovation and cost-efficiency
Teamwork and self-reliance
Scientific curiosity and planning
Map Skill
On the outline map of India, show the location of Indian space research centres.
Answer – Sriharikota – Space launch site (Andhra Pradesh)
Bangalore – ISRO headquarters (Karnataka)
Thiruvananthapuram – VSSC (Kerala)
Ahmedabad – SAC (Gujarat)
(Locate them on a political map of India.)
Something To Do
- Prepare a model (working or static) of the Solar System.
Answer – Use thermocol, clay, or paper balls for planets and arrange them in orbit around a Sun made of yellow craft ball.
- When was Mars Orbiter Mission (MOM) launched by India? What are its achievements and why it is so important for us?
Answer – Launched on November 5, 2013
Reached Mars on September 24, 2014
India became the first country to reach Mars in its first attempt
It showed India’s capability in space research at low cost
Collect pictures related to the landing of man on the moon and make a scrap file. You may also collect information about dates on which certain celestial bodies like Mars were seen from the earth.
Answer – Add photos of Apollo 11 Moon landing, Chandrayaan missions, MOM, Halley’s Comet, phases of the moon, and Mars as seen from Earth.
Include dates and facts about celestial sightings and space milestones.
Additional Questions And Answers – 01
Fill in the Blanks (with Answers)
- The planet known as the “Blue Planet” is ________________.
Answer – Earth - ________________ is the natural satellite of the Earth.
Answer – Moon - The planet with the largest number of moons is ________________.
Answer – Jupiter - A ________________ is a celestial body that revolves around a planet.
Answer – satellite - ________________ are known as the building blocks of planets.
Answer – Asteroids - ________________ are icy bodies that develop tails when they approach the Sun.
Answer – Comets - The Sun is a ________________ star.
Answer – medium-sized - The ________________ protects Earth from harmful solar radiation.
Answer – atmosphere - The Moon completes one revolution around the Earth in about ________________ days.
Answer – 27.3 - ________________ was the first Indian satellite.
Answer – Aryabhata
Multiple Choice Questions (MCQs)
- Which planet has the shortest day?
(a) Earth
(b) Jupiter
(c) Saturn
(d) Venus
Answer – (b) Jupiter - Which planet rotates in the opposite direction of most other planets?
(a) Mars
(b) Venus
(c) Earth
(d) Mercury
Answer – (b) Venus - Which of these is not a gas giant?
(a) Jupiter
(b) Saturn
(c) Neptune
(d) Mars
Answer – (d) Mars - Which star is closest to Earth?
(a) Proxima Centauri
(b) Sirius
(c) Sun
(d) Polaris
Answer – (c) Sun - What is the name of NASA’s first successful Mars rover?
(a) Pathfinder
(b) Curiosity
(c) Spirit
(d) Opportunity
Answer – (a) Pathfinder
True/False Questions (with Answers)
- Earth is the largest planet in the solar system.
False - Mercury has no atmosphere.
True - The Moon has its own light.
False - A comet’s tail always points away from the Sun.
True - Uranus rotates on its side.
True - The solar system has only 7 planets.
False - Mars is also called the “Red Planet.”
True - Stars change their position in the night sky.
True
Short Answer Questions
- What is a constellation?
A constellation is a group of stars forming a recognizable pattern in the sky, like Orion or Ursa Major. - Why is the Sun important for life on Earth?
It provides light and heat, making life possible and supporting plant growth. - Name any two artificial satellites of India.
INSAT, GSAT - Why is Earth suitable for life?
Because it has water, air, suitable temperature, and atmosphere. - What is a meteor shower?
When many meteors enter Earth’s atmosphere and burn up, it creates a meteor shower.
Competency-Based Reasoning and Assertion Questions
- Assertion: Venus is hotter than Mercury.
Reason: Venus has a thick atmosphere of carbon dioxide that traps heat.
Options:
(a) Both A and R are true, and R is the correct explanation of A.
(b) Both A and R are true, but R is not the correct explanation of A.
(c) A is true, but R is false.
(d) A is false, but R is true.
Answer – (a) - Assertion: The moon shines at night.
Reason: It reflects light from the Sun.
Answer – (a) Both A and R are true, and R is the correct explanation of A. - Assertion: Jupiter is known as the Gas Giant.
Reason: It is made mostly of hydrogen and helium gases.
Answer – (a) - Assertion: Stars appear to move in the sky.
Reason: Earth rotates on its axis.
Answer – (a)
Higher Order Thinking Skill (HOTS) Questions
- If the Earth stopped rotating, what would happen to day and night?
Answer: One side of the Earth would have constant day, while the other side would have constant night, severely affecting life, weather, and temperature. - Why do astronauts wear space suits in space?
Answer: Because space has no air or pressure, and temperatures can be extreme. The suit provides oxygen, pressure, and temperature control. - Why are telescopes placed in space and not just on Earth?
Answer: To avoid atmospheric distortion and get clearer images of distant celestial bodies. - Why is Mars a good candidate for human colonization?
Answer: It has water in the form of ice, a day length similar to Earth, and manageable gravity, although it still lacks oxygen and breathable atmosphere.
Long Answer Questions (Word Limit: 40–50 words)
- Explain how the phases of the Moon occur.
The Moon orbits the Earth, and we see different portions of its sunlit side. These changing shapes are called phases. They include new moon, crescent, half moon, gibbous, and full moon, repeating every 29.5 days. - Describe the importance of the Sun in our solar system.
The Sun provides energy and light that support life on Earth. It controls the movement of planets through gravity and helps maintain the climate, weather, and seasons. - Write about Chandrayaan-2 mission.
Chandrayaan-2 was India’s second lunar mission, launched in 2019. It aimed to explore the Moon’s south pole. Although the lander failed, the orbiter continues to send valuable data about the Moon’s surface and minerals. - What are artificial satellites? Mention their uses.
Artificial satellites are man-made objects placed in orbit around Earth. They are used for communication, weather forecasting, navigation (GPS), and scientific research like space observation.
Additional Questions And Answers – 02
Fill in the Blanks Questions and Answers
- The vast limitless space that includes all celestial bodies is called the __________.
Answer: Universe - A huge cluster of billions of stars, gas, and dust is called a __________.
Answer: Galaxy - The Solar System is located in the _________ Arm of the Milky Way Galaxy.
Answer: Orion - The nearest star to Earth, other than the Sun, is __________.
Answer: Proxima Centauri - The distance covered by light in one year is called a __________.
Answer: Light year - The group of stars that form recognizable patterns in the sky is called a __________.
Answer: Constellation - The stationary star above the North Pole is called the __________.
Answer: Pole Star - The Sun and its companion celestial bodies constitute the __________.
Answer: Solar System - The smallest planet in our Solar System is __________.
Answer: Mercury - The only planet known to support life is __________.
Answer: Earth - The Moon’s rotation and revolution period around Earth is _________ days.
Answer: 27.3 - The celestial bodies that revolve around planets are called __________.
Answer: Satellites - A depression formed by a meteor or volcanic eruption is called a __________.
Answer: Crater - Comets are small bodies with a head and a long luminous __________.
Answer: Tail - The Asteroid Belt is located between the orbits of __________ and __________.
Answer: Mars, Jupiter
Multiple Choice Questions (MCQs) and Answers
- What is the primary source of heat and light for the Solar System?
a) Moon
b) Sun
c) Jupiter
d) Proxima Centauri
Answer: b) Sun - Which planet is known as the Red Planet?
a) Venus
b) Mars
c) Jupiter
d) Mercury
Answer: b) Mars - How many planets are there in our Solar System?
a) Seven
b) Eight
c) Nine
d) Ten
Answer: b) Eight - Which constellation is also known as the Great Bear?
a) Orion
b) Ursa Major
c) Saptarishi Mandal
d) Pole Star
Answer: b) Ursa Major - Which planet is the hottest due to its volcanic activities and thick atmosphere?
a) Mercury
b) Venus
c) Earth
d) Mars
Answer: b) Venus - What is the name of the comet that appears every 76 years?
a) Hyakutake
b) Hale-Bopp
c) Halley’s Comet
d) Shoemaker-Levy
Answer: c) Halley’s Comet - Which planet has the most prominent rings visible from Earth?
a) Jupiter
b) Saturn
c) Uranus
d) Neptune
Answer: b) Saturn - What is the term for the distance covered by light in one year?
a) Astronomical Unit
b) Light Year
c) Parsec
d) Kilometer
Answer: b) Light Year - Which planet has no satellites?
a) Earth
b) Mars
c) Mercury
d) Jupiter
Answer: c) Mercury - What causes stars to appear to twinkle in the night sky?
a) Their size
b) Atmospheric disturbance
c) Their temperature
d) Their distance from Earth
Answer: b) Atmospheric disturbance
True/False Questions and Answers
- Stars are self-luminous celestial bodies.
Answer: True - The Sun is the farthest star from Earth.
Answer: False (The Sun is the nearest star to Earth.) - All planets in the Solar System have their own light and heat.
Answer: False (Planets reflect light from the Sun.) - The Moon’s rotation and revolution periods are the same.
Answer: True - Pluto is still considered a planet in the Solar System.
Answer: False (Pluto is classified as a dwarf planet.) - The Solar System is located in the Orion Arm of the Milky Way Galaxy.
Answer: True - The Earth is the only planet with an atmosphere that supports life.
Answer: True - Asteroids are found primarily between the orbits of Mars and Jupiter.
Answer: True - The Moon has an atmosphere similar to Earth’s.
Answer: False (The Moon has no significant atmosphere.) - Constellations are groups of stars that form recognizable patterns.
Answer: True
Short Questions and Answers
- What is a galaxy?
Answer: A galaxy is a huge cluster of billions of stars, gas, and dust held together by gravitational force. - Name the star closest to Earth besides the Sun.
Answer: Proxima Centauri - What is a light year?
Answer: A light year is the distance light travels in one year, approximately 3 lakh km per second for 365 days. - What is a constellation?
Answer: A constellation is a group of stars that form a recognizable pattern or shape in the night sky. - Name the eight planets in our Solar System in order of their distance from the Sun.
Answer: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune - Why does the Moon only show one side to Earth?
Answer: The Moon’s rotation and revolution periods are the same (27.3 days), so one side always faces Earth. - What are asteroids?
Answer: Asteroids are rocky objects that orbit the Sun, primarily found in the Asteroid Belt between Mars and Jupiter. - Why is Venus the hottest planet?
Answer: Venus is the hottest planet due to its volcanic activities and thick atmosphere, which trap heat. - What is the Pole Star?
Answer: The Pole Star, or Dhruv Tara, is a stationary star above the North Pole that indicates the north direction. - What is a meteor?
Answer: A meteor is a meteoroid that enters Earth’s atmosphere and burns up, creating a bright trail (shooting star).
Competency-Based Questions and Answers (Reasoning and Assertion)
- Assertion: The Earth is the only planet that supports life.
Reason: The Earth has an optimum amount of heat, light, and oxygen, along with water and an atmosphere that protects life.
Answer: Both assertion and reason are true, and the reason correctly explains the assertion. - Assertion: Stars appear to twinkle in the night sky.
Reason: Disturbances in Earth’s atmosphere cause starlight to bend, making stars appear to twinkle.
Answer: Both assertion and reason are true, and the reason correctly explains the assertion. - Assertion: The Moon has no atmosphere.
Reason: The Moon’s surface experiences extreme temperature changes due to the lack of an atmosphere.
Answer: Both assertion and reason are true, and the reason supports the assertion. - Assertion: Planets do not emit their own light.
Reason: Planets reflect light received from the Sun.
Answer: Both assertion and reason are true, and the reason explains the assertion. - Assertion: The Solar System is part of the Milky Way Galaxy.
Reason: The Milky Way is a barred spiral galaxy containing the Orion Arm, where the Solar System is located.
Answer: Both assertion and reason are true, and the reason supports the assertion.
High Order Thinking Skill (HOTS) Questions and Answers
- Why do you think the Earth is considered a unique planet in the Solar System?
Answer: The Earth is unique because it has the right conditions for life, including moderate heat and light from the Sun, abundant water covering two-thirds of its surface, and an atmosphere with oxygen and protection from meteoroids, unlike other planets that are too hot, cold, or lack these essentials. - How does the same rotation and revolution period of the Moon affect its visibility from Earth?
Answer: The Moon’s rotation and revolution periods are both 27.3 days, causing tidal locking. This means only one side of the Moon faces Earth, while the other side remains invisible, as the same side is always oriented toward us during its orbit. - Why do you think the Sun is critical to the Solar System’s structure?
Answer: The Sun’s massive gravitational pull holds all celestial bodies in the Solar System, including planets, asteroids, and comets, in their orbits. Its heat and light provide the energy necessary for life on Earth and influence the physical conditions of other planets. - How might the absence of an atmosphere on the Moon affect its surface conditions compared to Earth?
Answer: Without an atmosphere, the Moon lacks protection from solar radiation and meteoroids, leading to extreme temperature swings (214°C during the day, -184°C at night) and a barren surface with craters. Earth’s atmosphere moderates temperature and protects life. - Why do you think constellations were important to ancient civilizations?
Answer: Constellations helped ancient civilizations navigate, track seasons, and develop calendars by observing star patterns. They also held cultural and religious significance, as people associated them with stories, myths, and celestial events.
Long Questions and Answers (40-50 Words)
- Explain how the Solar System was formed according to scientific theories.
Answer: About 4.6 billion years ago, a giant cloud of gas and dust, called a nebula, cooled and rotated rapidly. The central mass formed the Sun, while eight gas balls separated to become planets, and smaller fragments became satellites, orbiting the Sun due to its gravitational pull. - Describe the characteristics that make Earth suitable for life.
Answer: Earth supports life due to its moderate heat and light from the Sun, abundant water covering two-thirds of its surface, and an atmosphere containing oxygen, water vapor, and dust particles. This atmosphere protects against meteoroids and maintains conditions ideal for sustaining diverse forms of life. - Why do stars appear to twinkle, and how is this different from planets?
Answer: Stars twinkle because atmospheric disturbances bend their light, causing it to flicker. Planets, being closer to Earth, appear as larger discs of light, so their light is less affected by atmospheric distortion, making them appear steady rather than twinkling in the night sky. - What are constellations, and how have they been used historically?
Answer: Constellations are groups of stars forming recognizable patterns in the sky, like Ursa Major. Historically, they were used by ancient civilizations, such as Indians and Greeks, for navigation, tracking seasons, and cultural storytelling, aiding in the development of calendars and astronomical studies. - Explain the significance of the Moon’s phases in cultural practices.
Answer: The Moon’s phases, from New Moon to Full Moon, determine lunar dates and months in cultures like Hindu and Muslim traditions. Festivals such as Deepawali and Eid are fixed based on these phases, reflecting their importance in religious and cultural calendars across India and Arab countries.