This article discusses asteroids and the danger from them.
|Asteroids are massive pieces of matter that orbit the sun. Most orbit between Mars and Jupiter. Asteroids are carbon rich, metallic and have silicate in them. June 30 is celebrated as the international asteroid day to commemorate the anniversary of the Tungushka asteroid impact over Siberia. 253 Mathilde is a C type asteroid of about 50 kilometres with craters on it. Such examples of asteroids exist among many in the international catalogue of asteroids. The danger we face is if one of them crashes into the earth. The Tungushka event is one such indicator and we have to know if there are other possibilities of such impact. The first asteroid to be discovered was Ceres in 1801. Some asteroids have moons about them. 243 Ida has a moon by the name of Dactyl. The three most closest asteroid groups to the earth are Apollo, Amors and Atens. Various deflection strategies have been proposed for them. Some near earth asteroids are 1221 Amor, 1862 Apollo, 2101 Adonis and 69230 Hermes. Near earth asteroids are being studied by a list of teams. Some of them are Lincoln Near Earth Asteroid Research, Near Earth Asteroid Tracking, Spacewatch and Lowell Observatory Near Earth Object search. The Lincoln Near Earth Asteroid Research has detected about 138,293 asteroids. Asteroids dimensions vary from 1000 km to 1 meter. The asteroid Ceres is the largest with a diameter of 1000 km. 4 Vesta and Pallas have diameters of 500 km.|