DAV Class 8 Science Chapter 17 Solutions Stars and Solar System of The Living World Science Book guides you with the answers to the questions given in the textbook. Class 8 is an important phase of the student’s life as they are introduced to many new concepts that are essential to set strong basics foundation for the topics to be taught in Class 9.
While solving chapter 17 of Science textbook, students often face several doubts and eventually get confused. To help class 8 students clear all their doubts instantly, DAV Class 8 Science Chapter 17 question answer Stars and Solar System come as a great resource. Here, the detailed Solutions for Class 8 Science Chapter 17 of Science book are given below.
These DAV Class 8 Science Chapter 17 Solutions Stars and Solar System will help you in scoring good marks as they cover important concepts in different patterns like fill in the blanks, Match the following, tick the correct option, Answer the following questions in brief and Answer the following questions.
Dav Class 8 Science Chapter 17 Question Answer Stars and Solar System
DAV Class 8 Science chapter 17 question answer Stars and Solar System, is given below. Here DAV Class 8 Science Chapter 17 solutions is provided with great explanation.
Highlights
- Fill in the blanks
- Match the following
- Tick the correct option
- Answer the following questions in brief
- Answer the following questions
Dav Class 8 Science Chapter 17 Question Answer Stars and Solar System of The Living World Science Book is the best study material for those students who are finding difficulties in preparing for their science exams. Students can also prepare their notes and other class assignments for free.
DAV Class 8 Science Chapter 17 Solutions
A. Fill in the blanks.
1. The spiral shaped galaxy, in which our solar system is located, is known as the ___________.
2. The various shapes, of the bright part of the moon, as seen by us during the month, are called ___________ of the moon.
3. The temperature on moon ranges from ___________ at ‘noon’ to ___________ at ‘night’.
4. The planet, known to have the largest number of natural satellites, as at present, is ___________.
5. The comet, which ‘visits’ the earth every 76 years, is the ___________.
6. Asteroids are found between the orbits of ___________ and ___________.
Answer: (1) Milky way (2) phases (3) 100°C, -173°C (4) Saturn (5) Halley’s Comet (6) Mars, Jupiter.
B. Match the following.
Answer: (1) b (2) f (3) d (4) a (5) c (6) e.
C. Tick the correct option.
1. A star is twenty light years away from the earth. Suppose it brightens up suddenly today. After how much time shall we see this change?
Answer: 20 years
2. Three stars A, B and C are observed in the night sky. The colours of these stars are: Star A: Blue colour, Star B: Red colour, Star C: White colour. The correct sequence, in terms of the increasing order of their surface temperature, is-
Answer: Star B < Star C < Star A
3. Stars, like the Sun, appear to move from east to west around the earth. This means that earth rotates from-
Answer: west to east
4. Phases of moon are observed because-
Answer: it is only sunlight, reflected by some parts of the moon that reaches the earth.
5. The change in seasons on the earth occurs because-
Answer: the axis of rotation of the earth is tilted with respect to its orbit.
6. The diagram shows the various positions of a comet in its orbit. In which position will the tail of the comet will appear to be longest?
Answer: position A
D. Answer the following questions in brief.
1. Name the first two stars closest to us.
Answer: Sun and Alpha Centauri.
2. Name the brightest star in the sky,
(a) during day time.
Answer: Sun is the brightest star in the sky during day time.
(b) during night.
Answer: Sirius is the brightest star in the sky during night.
3. Identify the planet with the help of the given clue.
(a) largest planet
Answer: Jupiter
(b) closest to the sun
Answer: Mercury
(c) this planet has two moons named, Phobos and Deimos
Answer: Mars
(d) red planet
Answer: Mars
(e) has a unique and special system of rings
Answer: Saturn
(f) has the largest number of moons
Answer: Saturn
(g) often known as morning or evening star
Answer: Venus
(h) named after the Roman Sea god
Answer: Neptune
4. Define the following.
(a) Milky way
Answer: The spiral shaped galaxy containing our Solar System is called the Milky Way.
(b) Celestial objects
Answer: The Natural objects that exist in outer space are called celestial objects.
(c) Pole star
Answer: The star which appears stationary from the earth is called Pole star.
(d) Constellation
Answer: A group of stars that make a recognisable pattern or shape in the sky is called Constellation.
(e) Asteroids
Answer: The minor planets that move around the sun between the orbits of Mars and Jupiter are called Asteroids.
(f) Geo-stationary Satellites
Answer: An earth orbiting satellite, with an orbital period the same as earth’s rotation period, nearly 24 hours are called Geo-stationary Satellites.
(g) Comets
Answer: A small icy object that orbits the sun and develops a long bright tail (of gases) when it passes near the sun.
(h) Light year
Answer: The distance covered by light in one year is called a Light year.
(i) Meteors
Answer: A piece of rock, or metal, that burns and glows brightly in the sky as it falls from outer space into the Earth’s atmosphere.
(j) Meteorites
Answer: A small piece of rock, or metal, that sometimes falls to the ground from outer space is called Meteorites.
5. Name the visible layer of the sun. Give an estimate of its temperature?
Answer: The visible layer of the sun is called the photosphere. Its temperature is 6000 K.
E. Answer the following questions.
1. How is Pole Star located in the sky? Explain with a diagram.
Answer: The Pole Star, known as the Dhruva Tara in Hindi, is a special star present in the northern hemisphere. This star, unlike the other stars, appears to be fixed at one place. In fact, all the stars appear to revolve around the pole star. This is so, because the pole star lies on a line close to the axis of rotation of the earth. The pole stare defines the north direction.
2. Differentiate between the following, giving examples:
(a) stars and constellations
Answer: Star is a single unit while a constellation is group of many stars. Sirius is a star while Orion is a constellation.
(b) stars and planets
Answer: Stars have their own light while planets do not have their own light. Alpha Centauri is a star while Mars is a planet.
(c) terrestrial planets and Jovian planets
Answer: Terrestrial planets are made up of rocks while Jovian planets are made up of gases. Mars is a terrestrial planet while Jupiter is a Jovian planet.
(d) artificial and natural satellite
Answer: Artificial satellite are man-made while natural satellite is formed through natural processes. Moon is a natural satellite while Aryabhata is an artificial satellite.
3. Identify, and name the constellations X, Y and Z and answer the following questions.
Answer: Constellations X is Orion; Constellations Y is Big Dipper and Constellations Z is Cassiopeia.
(a) Name the constellation that can be used to locate star Sirius?
Answer: Orion.
(b) Name the constellation that can be used to locate the Pole Star.
Answer: Big Dipper
(c) Name the constellations visible during the-
(i) spring season
Answer: Ursa Major.
(ii) winter season
Answer: Cassiopeia.
(d) Name the stars A and B in the constellation marked as ‘X’
Answer: A is Betelgeuse and B is Riget.
4. Give reasons for the following.
(a) Uranus is observed to have a ‘blue-green’ colour.
Answer: Uranus is observed to have a blue green colour because of presence of methane in its cold and clear atmosphere.
(b) Venus is the hottest planet even though Mercury is closest to the sun.
Answer: Venus is the hottest planet even though Mercury is closest to the sun because there is very high percentage of carbon dioxide in the atmosphere of Venus. This created greenhouse effect making Venus the hottest planet.
(c) The shape and size of bright side of moon appears to change (gradually) every day.
Answer: The period of rotation and revolution of the moon is same. Due to this relative position of the earth, the sun and the bright portion of the moon keeps on changing every day. Hence the shape and size of the bright side of moon appears to change gradually every day.
(d) A star appears to rise four minutes earlier in the sky everyday than the previous day.
Answer: A star appears to rise four minutes earlier in the sky everyday than the previous day because of revolution and rotation of the earth. The apparent position of the star changes on a daily basis due to this.
(e) Comets become visible only when they are near the sun.
Answer: Comets are visible only when they are near the sun. This is because the intense solar heat vaporises parts of their icy matter and creates their characteristic illuminated tail.
5. State, in brief, how artificial satellites are used in transmitting television programmes over large distances.
Answer: Artificial satellites are man-made objects which can be made to revolve around the earth. These satellites stay in the same position relative to the surface of the earth; hence the broadcasting station does not lose contact with the receiver.
A satellite receives a microwave signal from a ground station on the earth. Its amplifiers first amplify it. Thereafter, its transmitters re-transmit the (amplified) signal back to a receiving station on earth at a different frequency. This is how artificial satellites are used in transmitting television programmes over large distances.
Good answers