Asteroids – UPSC Prelims

Asteroids are small, airless rocky worlds revolving around the sun that are too small to be called planets. They are also known as planetoids or minor planets.

In total, the mass of all the asteroids is less than that of Earth’s moon. But despite their size, asteroids can be dangerous. Many have hit Earth in the past, and more will crash into our planet in the future.

Asteroid : A relatively small, inactive, rocky body orbiting the Sun.

Comet: A relatively small, at times active, object whose ices can vaporize in sunlight forming an atmosphere (coma) of dust and gas and, sometimes, a tail of dust and/or gas.

Meteoroid: A small particle from a comet or asteroid orbiting the Sun.

Meteor: The light phenomena which results when a meteoroid enters the Earth’s atmosphere and vaporizes; a shooting star.

Meteorite: A meteoroid that survives its passage through the Earth’s atmosphere and lands upon the Earth’s surface.

Most asteroids lie in a vast ring between the orbits of Mars and Jupiter.

Not everything in the main belt is an asteroid, for instance, comets have recently been discovered there, and Ceres, once thought of only as an asteroid, is now also considered a dwarf planet.

Many asteroids lie outside the main belt. For instance, a number of asteroids called Trojans lie along Jupiter’s orbital path.

Three groups — Atens, Amors, and Apollos — known as near-Earth asteroids orbit in the inner solar system and sometimes cross the path of Mars and Earth.