Earth-crossing asteroid

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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 perihelion less than the Earth's perihelion. A more precise definition of an Earth-Crossing Asteroid is one "whose orbit cross section can intersect the capture cross section of the Earth as a result of secular gravitational perturbations".

[edit] See also

• 2004 HR56

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