selenelion

plural selenelions · alternative selenehelion

1. A lunar eclipse occurring as the Moon sets, simultaneously with sunrise.

   I decided to watch for an uncommon eclipse phenomenon known as selenelion, seeing the Sun near the horizon and the eclipsed Moon near the opposite horizon at the same time.

   2010 June 26, Kelly Beatty, “In Search of Selenelion”, in Sky & Telescope

   4 more examples

   This phenomenon is called a "horizontal eclipse" or, from a French term, "selenelion." ... In modern times, the first record seems to date from 1590, when the great astronomer Tycho Brahe saw a selenelion from his observatory ....

   2001, Paul Davies, Duncan Steel, Eclipse: The Celestial Phenomenon That Changed the Course of History (Joseph Henry Press) p. 57

   2007, William Poole, "Antoine-François Payen, the 1666 Selenelion, and a Rediscovered Letter to Robert Hooke", Notes and Records of the Royal Society of London, Vol. 61, No. 3 (Sep. 22, 2007), pp. 251-263 JSTOR This he immediately published, under the title Selenelion ou Apparition Luni-Solaire .... The coinage ‘selenelion’ was his own .... Payen asserted that refraction on its own could not account for a selenelion...

   On Oct. 8, Interested skywatchers should attempt to see the total eclipse of the moon and the rising sun simultaneously. The little-used name for this effect is called a "selenelion," a phenomenon that celestial geometry says cannot happen.

   2014, Joe Rao, Total Lunar Eclipse On Wednesday Will Be a Rare 'Selenelion'

   Meteorologist Joe Rao points out that this eclipse presents an unusual chance to try seeing a selenelion: when the Sun and eclipsed Moon are both above the horizon at once.

   2014 October, Alan MacRobert, “Eclipse of a Large Moon”, in Sky & Telescope, page 52

   Synonyms: horizontal eclipse