What's the difference between perihelion and perihelium?
Perihelion
Definition:
(n.) Alt. of Perihelium
Example Sentences:
(1) It then plunges into the Sun's glare as it tracks towards perihelion, where it sweeps only 1,165,000 km above the Sun's surface on 28 November.
(2) Recall, too, that it was the then inexplicable Michelson-Morley experiment which encouraged the spread of Einstein's early ideas, and the baffling perihelion precession of Mercury which lent support to his general theory.
(3) After perihelion, and assuming enough of it has survived its scorching journey, ISON then reappears, tail first and moving northwards, to climb away from the Sun in both our morning and evening twilight.
Perihelium
Definition:
(n.) That point of the orbit of a planet or comet which is nearest to the sun; -- opposed to aphelion.