An Etymological Dictionary of Astronomy and Astrophysics

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فرهنگ ریشه‌شناختی اخترشناسی-اخترفیزیک

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potentially hazardous asteroid (PHA)
  سیارک ِ توندانه آپه‌ناک  
seyyârak-e tavandâné âpenâk
Fr.: astéroïde potentiellement dangereux  

An asteroid that could make a threatening close approach to the Earth. In technical terms a PHA is defined as having an → absolute magnitude of 22 or brighter and an → Earth Minimum Orbit Intersection Distance (MOID) of less than 0.05 → astronomical unit or 7.5 million km.

See also: → potentially; → hazardous; → asteroid.