Asteroids are a series of very small planets or fragments of planets lying between the orbits of Mars and Jupiter. Also called ‘Planetoids or small planets’.
They revolve around the sun in the same way as the planets.
They are too small to retain any atmosphere of their own.
Asteroids are presumed to be the remnants of matter that did not clump during the formation of the solar system. Even if the materials did collide, the gravity from Jupiter pulled them apart from each other.
Composed of rock, dust and metal, the early asteroids were formed when the heavy metal within them sunk to the centre of the rock, forming a metal core.
Over time, the lighter rocks formed layers around the core. The rock would then cool steadily, eventually becoming a solid.
Currently, the largest object in the asteroid belt, Ceres, at about 950 km diametre, has been placed under Dwarf Planet category.
Earth Planets : In Figures
Scheduled Caste ( SC ) 07 04
Scheduled Tribe ( ST )
2.3 Socially and Educationally Backward Classes :
Weak and Under Privileged Classes / SocialCastes ( OSC ) 12 01
Resident of Backward Areas Class ( RBA ) 13 10
2.3.3 Residents of Area Adjoining Actual Line of Control ( ALC )
Children of Defence Personnel / Military Forces and State Police Personnel ( CDP ) 15 02
Candidate possessing outstanding Proficiency in sports ( SP ) 16 01
2.6 Open merit category other than item (1) above who have served for a minimum period of 5 years in Rural Areas ( RS ) 22 10
- It has a head and a tail. Its tail originates only when it gets closer to the sun. The tail can be 20-30 million km long. It always point away from the sun because of the force exerted by solar wind and radiation on the cometory material.
- Comets may originate in a huge cloud called the Oort cloud that is thought to surround the Solar System.
- Hailey’s comet : Reappears after 76 years. Last seen in 1986.
- Comet Smith-Tuttle: Can collide with earth on Aug 17, 2116. Will create an impact of about 1.6 million times that of Hiroshima bomb.
- Comet Shoemaker Levy-9: Collided with Jupiter between July 16 and 21, 1994.
Meteors (Shooting Stars)
- The meteors are probably the remains of comets which are scattered in the inter-planetary space of the Solar System. On contact with the earth’s atmosphere, they burn due to friction.
- Sometimes an unusually large number of meteors can be seen in rapid succession. Such a display is called a meteor shower and occurs when the earth passes through a swarm of meteoroids.
- Largest known is of 70 tons, which landed in Namibia in pre-historic times.
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