- An asteroid whose orbit crosses the Earth's orbit, or whose orbit is being changed by Earth's gravity, and will some day cross the Earth's orbit. There are two types of Earth-approach Asteroids. Apollo Asteroids, which cross the Earth's orbit at the present time, and Amor and Aten Asteroids, which do not cross the Earth's orbit at the present time.
The writer's dictionary of science fiction, fantasy, horror and mythology. 2014.
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Earth-crossing asteroid — Asteroid whose path around the Sun crosses Earth s orbit. Three groups of such asteroids Aten, Apollo, and Amor asteroids are distinguished by the size of their orbits and how closely they approach the Sun. The Atens and Apollos cross Earth s… … Universalium
Asteroid — An object orbiting the Sun, that is smaller than a planet and has no atmosphere or any type of activity associated with comets. There are three types of asteroids. Irons (5.7%) made of mainly iron and nickel; Stones (92.8%) made of silicates;… … The writer's dictionary of science fiction, fantasy, horror and mythology
Asteroid deflection strategies — are methods by which near Earth objects could be diverted, preventing potentially catastrophic impact events. A sufficiently large impact would cause massive tsunamis and/or, by placing large quantities of dust into the stratosphere blocking… … Wikipedia
asteroid — asteroidal, adj. /as teuh royd /, n. 1. Also called minor planet. Astron. any of the thousands of small bodies of from 480 miles (775 km) to less than one mile (1.6 km) in diameter that revolve about the sun in orbits lying mostly between those… … Universalium
Asteroid-impact avoidance — Planetary defense redirects here. For defending against alien invasion in fiction, see alien invasion. Artist s impression of a major impact event. The collision between Earth and an asteroid a few kilometres in diameter releases as much energy… … Wikipedia
Asteroid mining — 433 Eros is a stony asteroid in a near Earth orbit Asteroid mining refers to the possibility of exploiting raw materials from asteroids and planetoids in space, including near Earth objects. Minerals and volatiles could be mined from an asteroid… … Wikipedia
earth — /errth/, n. 1. (often cap.) the planet third in order from the sun, having an equatorial diameter of 7926 mi. (12,755 km) and a polar diameter of 7900 mi. (12,714 km), a mean distance from the sun of 92.9 million mi. (149.6 million km), and a… … Universalium
Earth Sciences — ▪ 2009 Introduction Geology and Geochemistry The theme of the 33rd International Geological Congress, which was held in Norway in August 2008, was “Earth System Science: Foundation for Sustainable Development.” It was attended by nearly… … Universalium
Earth impact hazard — ▪ astronomy Introduction the danger of collision posed by astronomical small bodies whose orbits (orbit) around the Sun carry them near Earth. These objects include the rocky asteroids and their larger fragments and the icy nuclei of comets.… … Universalium
Earth and Space Sciences — ▪ 1996 Introduction GEOLOGY AND GEOCHEMISTRY In 1995 significant developments took place in the realm of geologic mapping, which provides the foundation for the presentation and comparison of data in the Earth sciences. The most important… … Universalium