Editing Lunar eclipse (section)

== {{anchor|Penumbral eclipse|penumbral lunar eclipse}}<!-- [[Penumbral eclipse]] redirects here -->Types of lunar eclipses ==
[[File:Geometry of a Lunar Eclipse.svg|thumb|A schematic diagram of the [[Earth's shadow|shadow]] cast by [[Earth]]. Within the [[umbra]], the central region, the planet totally shields direct [[sunlight]]. In contrast, within the [[penumbra]], the outer portion, the sunlight is only partially blocked. (Neither the [[Sun]], [[Moon]], and Earth sizes nor the distances between the bodies are to scale.)]] [[Earth's shadow]] can be divided into two distinctive parts: the [[umbra]] and [[penumbra]].{{Sfn|Link|1969|p=1}} Earth totally occludes direct [[solar radiation]] within the umbra, the central region of the shadow. However, since the Sun's [[angular diameter|diameter appears]] to be about one-quarter of Earth's in the [[Extraterrestrial skies#The Moon|lunar sky]], the planet only partially blocks direct [[sunlight]] within the penumbra, the outer portion of the shadow.

=== Penumbral lunar eclipse ===
A penumbral lunar eclipse occurs when part or all of the Moon's near side passes into the Earth's penumbra.{{Sfn|Link|1969|p=2}} No part of the moon is in the Earth's umbra during this event, meaning that on all or a part of the Moon's surface facing Earth, the sun is partially blocked. The penumbra causes a subtle dimming of the lunar surface, which is only visible to the naked eye when the majority of the Moon's diameter has immersed into Earth's penumbra.<ref>{{Cite book |last=H. Mucke |first=J. Meeus |title=Canon of Lunar Eclipses -2002 to +2526 |date=1992 |publisher=Astronomisches Büro Wien |edition=3rd |page=V|bibcode=1992cle..book.....M }}</ref> A special type of penumbral eclipse is a ''[[total penumbral lunar eclipse]]'', during which the entire Moon lies exclusively within Earth's penumbra. Total penumbral eclipses are rare, and when these occur, the portion of the Moon closest to the umbra may appear slightly darker than the rest of the lunar disk.

=== Partial lunar eclipse ===
[[File:Eclipse_lunar_2019.gif|thumb|Latter phases of the partial [[July 2019 lunar eclipse|lunar eclipse on 17 July 2019]] taken from [[Gloucestershire]], [[United Kingdom]]]]
When the Moon's near side penetrates partially into the Earth's umbra, it is known as a partial lunar eclipse,{{Sfn|Link|1969|p=2}} while a ''total lunar eclipse'' occurs when the entire Moon enters the Earth's umbra. During this event, one part of the Moon is in the Earth's umbra, while the other part is in the Earth's penumbra. The Moon's average [[orbital speed]] is about {{convert|2300|mph|km/s|abbr=on|sigfig=3|order=flip}}, or a little more than its diameter per hour, so totality may last up to nearly 107 minutes. Nevertheless, the total time between the first and last contacts of the Moon's limb with Earth's shadow is much longer and could last up to 236 minutes.<ref>{{Cite book |last=Karttunen |first=Hannu |url=https://books.google.com/books?id=DjeVdb0sLEAC&pg=PA139 |title=Fundamental Astronomy |date=2007 |publisher=Springer |isbn=9783540341444 |page=139}}</ref>

=== Total lunar eclipse ===
[[File:2007-03-03 - Lunar Eclipse small-43img.gif|thumb|left|Timelapse of the total lunar eclipse on 4 March 2007.]]
When the Moon's near side entirely passes into the Earth's umbral shadow, a total lunar eclipse occurs.{{Sfn|Link|1969|p=2}} Just prior to complete entry, the brightness of the lunar limb—the curved edge of the Moon still being hit by direct sunlight—will cause the rest of the Moon to appear comparatively dim. The moment the Moon enters a complete eclipse, the entire surface will become more or less uniformly bright, being able to reveal stars surrounding it. Later, as the Moon's opposite limb is struck by sunlight, the overall disk will again become obscured. This is because, as viewed from the Earth, the brightness of a lunar limb is generally greater than that of the rest of the surface due to reflections from the many surface irregularities within the limb: sunlight striking these irregularities is always reflected back in greater quantities than that striking more central parts, which is why the edges of full moons generally appear brighter than the rest of the lunar surface. This is similar to the effect of [[velvet]] fabric over a convex curved surface, which, to an observer, will appear darkest at the center of the curve. It will be true of any planetary body with little or no atmosphere and an irregular cratered surface (e.g., Mercury) when viewed opposite the Sun.<ref>{{cite web|url=https://astronomy.com/magazine/stephen-omeara/2018/11/copy-of-lunar-limb-magic|title=Lunar Limb Magic|work=Astronomy.com|date=27 November 2018}}</ref>

=== Central lunar eclipse ===
Central lunar eclipse is a total lunar eclipse during which the Moon passes near and through the centre of Earth's shadow, contacting the [[antisolar point]].<ref>{{Cite book |last1=Westfall |first1=John |title=Celestial Shadows: Eclipses, Transits, and Occultations |last2=Sheehan |first2=William |publisher=Springer |year=2014 |isbn=978-1493915354 |pages=50}}</ref> This type of lunar eclipse is [[list of central lunar eclipses|relatively rare]].

The [[lunar distance (astronomy)|relative distance]] of the Moon from Earth at the time of an eclipse can affect the eclipse's duration. In particular, when the Moon is near [[apogee]], the farthest point from Earth in [[orbit of the Moon|its orbit]], its [[orbital speed]] is the slowest. The diameter of Earth's umbra does not decrease appreciably within the changes in the Moon's orbital distance. Thus, the concurrence of a totally eclipsed Moon near apogee will lengthen the duration of totality.

=== Selenelion ===
[[File:Lunar eclipse at sunrise Minneapolis October 2014.png|thumb|[[October 2014 lunar eclipse]] viewed from [[Minneapolis]] during [[sunrise]] on 8 October 2014. Both the Moon and Sun were visible at that time.<ref>{{Cite web |title=Day and Night World Map |url=https://www.timeanddate.com/worldclock/sunearth.html?day=8&month=10&year=2014&hour=7&min=25&sec=0&n=159&ntxt=Minneapolis&earth=0 |access-date=1 November 2023 |website=www.timeanddate.com |language=en}}</ref>]]
A ''selenelion'' or ''selenehelion'', also called a ''horizontal eclipse'', occurs where and when both the Sun and an eclipsed Moon can be observed at the same time. The event can only be observed just before [[sunset]] or just after [[sunrise]], when both bodies will appear just above opposite [[horizon]]s at nearly [[opposition (planets)|opposite points]] in the sky. A selenelion occurs during every total lunar eclipse—it is an experience of the ''observer'', not a planetary ''event'' separate from the lunar eclipse itself. Typically, observers on Earth located on high mountain ridges undergoing [[false sunrise]] or [[false sunset]] ''at the same moment of a total lunar eclipse'' will be able to experience it. Although during selenelion the Moon is completely within the Earth's umbra, both it and the Sun can be observed in the sky because [[atmospheric refraction]] causes each body to [[Mirage#Superior mirage|appear higher]] (i.e., more central) in the sky than its true geometric planetary position.<ref>{{Cite web |author=Kelly Beatty |title=In Search of Selenelion |date=26 June 2010 |url=http://www.skyandtelescope.com/community/skyblog/observingblog/97224024.html |website=[[Sky & Telescope]] |url-status=dead |archive-url=https://web.archive.org/web/20111220123836/http://www.skyandtelescope.com/community/skyblog/observingblog/97224024.html |archive-date=20 December 2011 |access-date=8 December 2011}}</ref>