Earth-crossing asteroid


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 orbit on an almost continuous basis, whereas only about half the Amors are Earth crossers and then only part of the time. Astronomers have mounted searches for objects that closely approach Earth, partly to determine whether they may collide with the planet, since early detection might make it possible to avert a catastrophe. According to some estimates, 1,000 Earth-crossing asteroids larger than 0.6 mi (1 km) may exist. Impacts of 0.6-mi-size asteroids are believed to occur a few times every million years. Such a collision would deliver the explosive force of several hydrogen bombs, possibly resulting in global climate disturbances or huge tidal waves. The impact of an object about 6 mi (10 km) in diameter is thought to have caused a massive extinction of species, including the dinosaurs, at the end of the Cretaceous Period.

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Universalium. 2010.

Look at other dictionaries:

  • Earth-crossing asteroid — An Earth Crossing Asteroid (ECA), is an asteroid that is capable of coming very near to the Earth at any point in the future. This is not to be confused with an Earth crosser asteroid, which has an aphelion greater than Earth s aphelion, and a… …   Wikipedia

  • List of Earth-crossing asteroids — An Earth crosser asteroid is a Near Earth asteroid whose orbit crosses that of Earth. The known numbered Earth crossers are listed here. Those Earth crossers whose semi major axes are smaller than Earth s are Aten asteroids; the remaining ones… …   Wikipedia

  • Planet-crossing asteroid survey — Le programme Palomar Planet Crossing Asteroid Survey (PCAS) a été lancé par Eleanor F. Helin et Eugene M. Shoemaker en 1973. Ce programme est à l origine de la découverte de plusieurs milliers d astéroïdes de tous types dont un grand nombre d… …   Wikipédia en Français

  • Planet Crossing Asteroid Survey — Le programme Palomar Planet Crossing Asteroid Survey (PCAS) a été lancé par Eleanor F. Helin et Eugene M. Shoemaker en 1973. Ce programme est à l origine de la découverte de plusieurs milliers d astéroïdes de tous types dont un grand nombre d… …   Wikipédia en Français

  • Planet-Crossing Asteroid Survey — The Palomar Planet Crossing Asteroid Survey (PCAS) was initiated by Eleanor F. Helin and Eugene M. Shoemaker in 1973. This program is responsible for the discovery of several thousand asteroids of all types including a large number of Near Earth… …   Wikipedia

  • Planet-Crossing Asteroid Survey — Le programme Palomar Planet Crossing Asteroid Survey (PCAS) a été lancé par Eleanor F. Helin et Eugene M. Shoemaker en 1973. Ce programme est à l origine de la découverte de plusieurs milliers d astéroïdes de tous types dont un grand nombre d… …   Wikipédia en Français

  • Planet-Crossing Asteroid Survey — Die Palomar Planet Crossing Asteroid Survey (PCAS) wurde im Jahr 1973 von Eleanor F. Helin und Eugene M. Shoemaker ins Leben gerufen. Das Ergebnis des Programms ist die Entdeckung mehrerer tausend Asteroiden aller Typen einschließlich einer… …   Deutsch Wikipedia

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  • 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


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