peri·​he·​lion | \ ˌper-ə-ˈhēl-yən How to pronounce perihelion (audio) \
plural perihelia\ ˌper-​ə-​ˈhēl-​yə How to pronounce perihelia (audio) \

Definition of perihelion

: the point nearest to the sun in the path of an orbiting celestial body (such as a planet) — compare aphelion

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Other Words from perihelion

perihelial \ ˌper-​ə-​ˈhēl-​yəl How to pronounce perihelial (audio) \ adjective

Examples of perihelion in a Sentence

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The last time a Mars opposition lined up with a Mars perihelion was in 2003, when Mars was at its brightest in the sky in roughly 60,000 years. Eileen Reslen, Popular Mechanics, "Look Up! Mars Is Brighter This Month Than It Has Been in 15 Years," 20 July 2018 Mars’ orbit is more elliptical than Earth’s, so the difference between perihelion and aphelion is greater. Dave Epstein,, "Mars is going to be really bright for the rest of the summer," 11 July 2018 Over the past centuries, Mars’ orbit has been getting more and more elongated, carrying the planet even nearer to the sun at perihelion and even farther away at aphelion. Dave Epstein,, "Mars is going to be really bright for the rest of the summer," 11 July 2018 Lescarbault’s sightings were never confirmed, and the perihelion precession of Mercury remained a puzzle for nearly six more decades. Katia Moskvitch, WIRED, "Troubled Times for Alternatives to Einstein’s Theory of Gravity," 6 May 2018 After orbiting the Earth for 6 hours, a third-stage burn-to-depletion was completed at approximately 02:30 UTC Feb 7, placing the dummy payload in a heliocentric orbit having a perihelion of 0.99 au and aphelion ~1.7 au. Joe Pappalardo, Popular Mechanics, "We Know Exactly Where Musk’s Space Tesla Is Going," 8 Feb. 2018 The Roadster and its mannequin driver -- known as Starman -- then will fall back toward the inner solar system, picking up speed as they near the low point of the orbit, or perihelion, on Aug. 15, 2019. William Harwood, CBS News, "Elon Musk's Tesla Roadster won't hit Earth anytime soon," 14 Feb. 2018 Each year, during wintertime in the northern hemisphere, the Earth reaches its closest point to the sun, or perihelion, and during the northern hemisphere summer the Earth hits the farthest point from the sun, or aphelion. Jay Bennett, Popular Mechanics, "One Day There Will Be No More Total Solar Eclipses," 18 Aug. 2017 Probe 1, the Pre-Perihelion Probe, would pass Halley on 8 December 1985, 63 days before the comet reached perihelion on 9 February 1986. David S. F. Portree, WIRED, "A Strategy for Comet Missions in the 1980s (1974)," 4 Aug. 2013

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'perihelion.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of perihelion

1666, in the meaning defined above

History and Etymology for perihelion

New Latin, from peri- + Greek hēlios sun — more at solar

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The first known use of perihelion was in 1666

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