Chapter Review:
- The stars, the planets, the moon and many other objects in the sky are called celestial objects.
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The day on which the whole disc of the moon is visible is known as the full moon day.
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The various shapes of the bright part of the moon as seen during a month are called phases of the moon.
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On the fifteenth day the moon is not visible. This day is known as the new moon day.
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The next day of the new moon day, only a small portion of the moon appears in the sky. This is known as the crescent moon.
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The distance travelled by light in one year known as light year.
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The stars forming a group that has a recognisable shape is called a constellation.
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A body revolving around another body is called a satellite.
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A planet has a definite path in which it revolves around the Sun. This path is called an orbit.
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The movement of planets around the sun on their orbit is called revolution.
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The planets move on their own axis like top, Such movement s known as rotation.
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Mars appears slightly reddish and, therefore, it is also called the red planet.
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Moon revolving round the Sun.
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The smallest planet is mercury.
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The mass of Jupiter is about 318 times that of our Earth.
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On July 21, 1969 (Indian time) the American astronaut Neil Armstrong
landed on the moon for the first time. -
There is a large gap in between the orbits of Mars and Jupiter. This gap is occupied by a large number of small objects that revolve around the Sun. These are called asteroids.
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However we may see a bright streaks of light falling in the sky. These are commonly known as shooting stars, although they are not stars. They are called meteors.
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The Sun is nearly 150,000,000 kilometres (150 million km) away from
the Earth. -
The artificial satellites revolve around the Earth. They are much closer than the moon.
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Venus is the brightest planet in the night sky.