On this page, you will find notes, questions, and answers to class 8 science chapter 17 Stars and The Solar System. These notes, explanations, examples, and questions and answers are according to CBSE and the NCERT textbook. If you like the study material, feel free to share the link as much as possible.
The stars appear to be moving from east to west.
The Pole star, also called Dhruvtara, appears stationary from the earth as it is situated in the direction of the earth's axis. It is also known as a stationary star. This makes the pole star useful for navigation purposes. That’s why stars are important.
What is special about Pole Star?
Pole stars appear stationary from any location on the planet. This is due to its location along the earth's axis of rotation. In the north, the pole star is located above the Earth.
Why do stars seem to twinkle?
Because of their large distance from the Earth and atmospheric disturbances, the stars appear to sparkle. It takes years for light from the stars to reach Earth.
The distance between Alpha Centauri (the next closest star after the sun) and the earth is approximately 40,000 billion kilometers, implying that stars are further distant from the planet than the sun.
The distance between the Sun and Earth
The distance from the sun to the earth is approximately 150,000,000 km or 150 million km.
A group of stars form a recognizable shape or pattern in the sky and are usually named after mythological characters, people, animals, and objects. There are 88 known constellations, of which only a few, like Ursa Major, Ursa Minor, Orion, Cassiopeia, and Leo Major can be identified with the naked eye.
The Moon revolves around the earth and doesn't have its own light. It reflects the light of the sun. That's why we are able to see the moon.
There are eight planets in our solar system.
The first four planets, such as Mercury, Venus, Earth, and Mars, are much nearer to the Sun and are called the inner planets. The inner planets are also known as terrestrial planets. The inner planets have very few moons.
The planets outside the orbit of Mars, namely Jupiter, Saturn, Uranus, and Neptune, are much farther off than the inner planets and are called the outer planets. The outer planets have a large number of moons.
Uranus and Neptune
Small objects which revolve around the sun and are found in between the orbits of Mars and Jupiter. It can only be seen through large telescopes.
A comet appears generally as a bright head and a glowing gaseous outer cloud called the coma. The comet revolves around the earth and when it reaches the sun, the coma spreads out in the form of a long tail.
A bright streak of light in the sky is commonly known as a shooting star. A small object that occasionally enters the earth’s atmosphere.
The small rocky pieces revolve around the sun. When a piece of the meteoroid survives the trip to earth and lands on earth, they are called meteoroids.
How do the days and nights occur?
Day and night occur due to the rotation of the earth. The Earth rotates on its own axis. It takes 24 hours to complete one rotation.
A celestial object that revolves around a planet.
Satellites are divided into two categories.
The artificial satellites which are man-made objects are much nearer to the Earth than its natural satellite.
Artificial satellites are used for a variety of purposes, including weather forecasting, the transmission of television and radio broadcasts, telecommunication, and remote sensing. Several artificial satellites have been created and launched by India.
The first artificial satellite launched by India was Aryabhatta in 1975.
Why are stars invisible during the daytime?
During the day and at night stars are present in the sky. During the day, however, the sunshine is so strong that it is difficult to see stars in the sky.
Why do stars appear moving from east to west?
The Earth spins in a west-to-east direction. The earth appears to be still to us, while the sky appears to be moving east to west. It is not, however, correct. The sun appears to rise in the east and set in the west for the same reason.
Can stars change their positions?
After observing a star or group of stars for a few hours, their location appears to change. This is due to the earth's motion. The earth is constantly revolving around the sun, thereby changing its position relative to the stars.
What is a lunar eclipse?
The lunar eclipse happens when the moon, Earth, and Sun are all very close to each other, with the Earth directly in the midst of the moon and the sun. As a result, the earth's shadow falls on the moon.
Thus, during a lunar eclipse, the moon does not reflect sunlight but rather the light it gets from the earth. During a lunar eclipse, the moon appears to be reddish in color.
What is the Moon Cycle?
The cycle is about 29 days, where it goes from a full moon to a new moon to a full moon.
What is Astronomy?
Astronomy is a branch of science that studies celestial bodies and their associated phenomena.
What are the different types of lunar phases?
Various shapes of the bright part of the moon seen during a month are known as the phases of the moon.
What is the dark side of the moon?
The part of the moon that always faces away from the earth is called the dark side of the moon.
What is the difference between a star and a constellation?
Stars are one of the celestial bodies which emit light of their own whereas Constellations are the group of stars that appear to form some recognizable shape or pattern is known as a constellation.
What is a satellite?
Any celestial body revolving around another celestial body is called its satellite.
What is the temperature of the moon?
If we talk about the temperature of the moon during the daytime it is 100 degrees Celsius and at night it is 168 degrees Celsius because of such inhabitable conditions.
What is the Full Moon Day?
The Full Moon day is when the whole disc of the moon facing towards the earth is visible to us.
What is the constellation of Big Dipper?
Ursa Major One of the most famous constellations which you can see during summertime, in the early part of the night. The seven big bright stars comprise this constellation. These stars resemble the form of a large interrogatory mark or a ladle. The ladle handle is done by connecting the 3 stars into a row, with the four other stars in the shape of the ladle's bowl.
Where is Sirius?
Sirius is the brightest star in the sky and it is located close to Orion.