Why Halley the comet has a tail, whereas Vesta the brightest asteroid does not have one?.


Halley's comet belongs to the comet group which are  made of ice,rock and dusty substances which orbit around the solar system in an elliptical orbit. They are formed from the  outer layers of the Sun. During their orbital travel when they are closer to the Sun, we see their ice melting and forming a fuzzy like tail on the Sky. The heat from the Sun causes ice and other materials on a comet’s surface to heat up until they vaporize. That vapor is what is seen as the comets tail.




A color image of comet Halley, shown flying to the left aligned flat against the sky


Vesta the brightest  asteroid belongs to the asteroid group that are made of metal, rocky substances. They orbit around the sun in small circular orbit closer to the sun . There are tens and thousands of them as an asteroid belt between Mars and Jupiter.



 Since they are made of dark metal they are dark in colour. There are only 3,572 known comets, but there are many millions of asteroids. Some as small as dust particles.



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