aph·elion /æˈfiljən/
  遠日點
  A·phel·ion n.; pl. Aphelia   Astron. That point of a planet's or comet's orbit which is most distant from the sun, the opposite point being the perihelion.
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  aphelion
       n : apoapsis in solar orbit; the point in the orbit of a planet
           or comet that is at the greatest distance from the sun
           [ant: perihelion]
       [also: aphelia (pl)]