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प्रश्न
Distinguish between the following pair.
Periodical and Non-periodical comets
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उत्तर
Periodical comets: The comets which have regular orbits around the Sun and occur at fixed intervals are called periodical comets. Halley’s comet is a periodical comet and is one of the most famous comets, which is due next in 2062. It is seen at intervals of 76 years. It was seen in 1910 and in 1986.
Non-periodical comets: Such comets are seen very rarely and they are not sighted at regular intervals. There are records of observations of about 1000 comets. Some of these have been named. Comets become visible only when they travel close to the Sun. The ice melts and the gas and dust are swept back to form the tail. The tail always points away from the Sun.
संबंधित प्रश्न
How can you prove that the earth is a sphere by looking at the horizon?
Fill in the blank:
A typical galaxy may contain ___________ stars.
Study the picture and answer the questions that follow.
(a) What does the picture show you about the earth?
(b) State briefly the Bedford Level Experiment.
(c) The sun rises and sets at different times in different places. What does the statement show the shape of the earth?
(d) In what way is the earth’s atmosphere beneficial to mankind?
Which planet has three rings around it?
Give a reason for the following:
Earth has the most ideal temperature conditions.
Arrange the nine planets of the solar system in order of their sizes.
Why is the following planet not inhabitable?
Venus
Give reasons for the following:
Venus is considered as the Earth’s twin.
Who am I?
No other planet has a living world like mine.
Who am I?
I am the nearest star to the earth.
