LEARNATHON
III

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Theory:

Another celestial member of the solar system family is the comets.
Comets are lumps of gas and dust which revolve around the Sun in highly elliptical orbits. They are visible only when they approach closer to the Sun. The revolution period of a comet is very long.
Parts of a comet:
The body of a comet is of two main parts; head and tail. A comet has a bright head with a long tail.
 
shutterstock204172201w1018jpg.jpg
A comet
 
When a comet approaches the sun, the condensed gases and dust particles on the body get heated up and vaporise, making the head glow. A comet's tail is always directed opposite to the direction of the sun.
 
comet path.png
Position of comet around the Sun
 
The biggest comets can even have a tail of \(160\ million\ km\) (or \(16\ crores\ km\)) long. This length is more than the distance between Earth and Sun. Some comets may appear periodically.
Halley’s comet:
Halley’s comet is a periodical comet, which appears after every \(76\ years\). Previously, it was seen in the year \(1986\) and will be visible again in the year \(2062\).
halleys.jpg
Halley’s comet in \(1986\)
 
Important!
Do you know!
In the olden days, people had so many myths and superstitions on a comet. They thought that the comets were messengers of disasters like wars, epidemics and floods.
Reference:
https://live.staticflickr.com/7210/6967153925_9716066eca.jpg
https://upload.wikimedia.org/wikipedia/commons/f/fc/Comet_tail_diagram.jpg