Most of the comets that enter the solar system originate in either the Oort Cloud or the Kuiper Belt, zones containing trillions of icy and rocky bodies orbiting in the furthest reaches of the sun's influence. Gravitational perturbations or collisions occasionally cause these comets to approach Earth.
The Oort Cloud is a large spherical cloud surrounding the solar system, and it is the source of most long-period comets that take more than 200 years to make a full orbit. The Kuiper Belt is a disc-shaped area of space beyond Neptune where most short-period comets originate. Both zones are believed to be remnants from the creation of the solar system around 4.6 billion years ago.Learn More
A comet is composed of dust, ammonia, ice, carbon dioxide and methane in addition to other substances. Ice and dust covered with an organic substance largely make up the nucleus of a comet. The tail of a comet consists of dust and gas.Full Answer >
Scientists predict that Halley's Comet, also known as Comet Halley, will make an appearance again in late 2061, early 2062. It was last seen in the sky in 1986.Full Answer >
Cosmic rays are fast-moving elementary particles, such as protons, electrons and atomic nuclei, that strike the Earth from outer space. They travel almost at the speed of light. Scientists believe they originate from supernovas, black holes and quasars.Full Answer >
Ukrainian scientists discovered a large asteroid in late 2013 that could possibly strike the Earth on Aug. 26, 2032. If such a collision occurred, it would strike with a force 50 times greater than the largest atomic bomb.Full Answer >