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Potentially Hazardous AsteroidA Potentially Hazardous Asteroid (PHA) is a Near-Earth asteroid that can come very close to the Earth and is big enough to cause at least a region-wide catastrophe if it were to hit the Earth. An asteroid is considered a PHA if its Earth MOID (Minimum Orbit Intersection Distance) is less than 0.05au and its absolute magnitude is greater than 22. By this definition, PHAs are usually bigger than 150m.
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