Page 19 - COSMOS & H -Health - Science

COMETS
COMETS

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WHAT ARE COMETS?
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WHAT ARE COMETS?
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A comet is a small, icy, solar system body. When passing
A comet is a small, icy, solar system body. When passing
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A A c o m e t t i i s a s m a l l l l , , i i c y , , s o l l a r s y s t t e m b o d y . . W h e n p a s s i i n g
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c c l l o s e t t o t t h e S u n , , c o m e t t s h e a t t u p a n d b e g i i n t t o o u t t g a s . . T h i i s
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close to the Sun, comets heat up and begin to outgas. This
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close to the Sun, comets heat up and begin to outgas. This
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causes them to display a visible atmosphere or coma.
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causes them to display a visible atmosphere or coma. .
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Sometimes, they also exhibit a tail. Comet nuclei can
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Sometimes, they also exhibit a tail. Comet nuclei can
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range from a few hundred meters across to tens of
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range from a few hundred meters across to tens of
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kilometers across. They are composed of loose collections
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kilometers across. They are composed of loose collections
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of ice, dust and small rocky particles.
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of ice, dust and small rocky particles.
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E E T Y M O L O G Y - -
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ETYMOLOGY-
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T T h e w o r d c o m e t t i i s d e r i i v e d f f r o m t t h e O l l d E n g l l i i s h “ c o m e t t a ” a n d f f r o m t t h e L a t t i i n
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The word comet is derived from the Old English “cometa” and from the Latin
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The word comet is derived from the Old English “cometa” and from the Latin
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word “cometes”. The word itself is a latinisation of the Greek phrase for
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word “cometes”. The word itself is a latinisation of the Greek phrase for
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“wearing long hair”
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“ “ w e a r i i n g l l o n g h a i i r ”
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“wearing long hair”
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NUCLEUS OF THE COMET-
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NUCLEUS OF THE COMET-
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T T h e n u c l l e u s i i s a s o l l i i d , , c o r e s t t r u c t t u r e o f f a c o m e t t . .
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The nucleus is a solid, core structure of a comet.
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The nucleus is a solid, core structure of a comet.
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I I It is composed of an amalgamation of rock, ,

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It is composed of an amalgamation of rock,

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dust, water ice and frozen gases. The gases are
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d d u s t t , , w a t t e r i i c e a n d f f r o z e n g a s e s . . T h e g a s e s a r e
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dust, water ice and frozen gases. The gases are

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methane and ammonia.
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Comets are popularly described as “dirty snowballs” due to Fred Whipple’s

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Comets are popularly described as “dirty snowballs” due to Fred Whipple’s
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model of comets. However, some comets may have higher dust content than
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the normal range.
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