imported>Weatherman4064: /* Related eclipses */

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Related eclipses

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{{short description|Extremely short lunar eclipse}}
{{Infobox lunar eclipse
| type = penumbral
| image = Lunar eclipse chart close-2016Aug18.png
| caption = The Moon barely clipped the northern penumbral shadow of the Earth.
| date = August 18, 2016
| gamma = 1.559
| magnitude = −0.9925
| saros_ser = 109
| saros_no = 72 of 72
| penumbral = 33 minutes, 36 seconds
| p1 = 9:25:36
| greatest = 9:42:24
| p4 = 9:59:12
| previous = March 2016
| next = September 2016
}}
A penumbral [[lunar eclipse]] occurred at the Moon’s [[Lunar node|descending node]] of orbit on Thursday, August 18, 2016,<ref>{{cite web|title=August 18, 2016 Almost Lunar Eclipse|url=https://www.timeanddate.com/eclipse/lunar/2016-august-18|publisher=timeanddate|access-date=16 November 2024}}</ref> with an umbral [[Magnitude of eclipse|magnitude]] of −0.9925. A lunar eclipse occurs when the [[Moon]] moves into the [[Earth's shadow]], causing the Moon to be darkened. A penumbral lunar eclipse occurs when part or all of the Moon's near side passes into the Earth's penumbra. Unlike a [[solar eclipse]], which can only be viewed from a relatively small area of the world, a lunar eclipse may be viewed from anywhere on the [[night]] side of Earth. Occurring about 3.4 days before [[Apsis|perigee]] (on August 21, 2016, at 21:20 UTC), the Moon's apparent diameter was larger.<ref>{{cite web|title=Moon Distances for London, United Kingdom, England|url=https://www.timeanddate.com/astronomy/moon/distance.html?year=2016&n=136|publisher=timeanddate|access-date=16 November 2024}}</ref>

The HM National Almanac Office's online canon of eclipses lists this event as the last eclipse on Saros Series 109,<ref name="HMNAO" /> while NASA lists August 8, 1998 as the last eclipse of the series, and has this event missing the shadow.<ref name="NEWS" />

This eclipse grazed the northern boundary of the Earth's penumbral shadow. The event lasted 33 minutes and 36 seconds, beginning at 9:25 [[UTC]] and ending at 9:59. This produced a maximum [[magnitude of eclipse|penumbral magnitude]] of 0.0166.{{sfn|Espenak|1989|p=150}} Eclipses of such small magnitudes are visually imperceptible; a penumbral magnitude of approximately 0.6 is required for even skilled observers to detect.{{sfn|Espenak|Meeus|2009|p=11}}

== Background ==
The Earth's penumbral shadow is larger than would be expected from simple geometry, a phenomenon first observed by [[Philippe de La Hire]] in 1707. The precise amount of enlargement varies over time for reasons which are not fully understood, but likely involve the amount of dust in certain layers of the Earth's atmosphere.{{sfn|Espenak|1989|p=205}} Various eclipse almanacs have used different assumptions about the magnitude of this effect, resulting in disagreement about the predicted duration of lunar eclipses or, in the case of penumbral eclipses of very short duration, whether the eclipse will occur at all.{{sfn|Espenak|1989|p=207}}

In 1989, [[NASA]] published a lunar eclipse almanac that predicted a short penumbral lunar eclipse to occur on 18 August 2016. However, the French almanac ''[[Connaissance des Temps]]'' used more conservative assumptions about the size of the Earth's shadow and did not predict an eclipse to occur at all.{{sfn|Espenak|1989|p=207}} The ''[[Bureau des Longitudes]]'' in France continued to refine their lunar eclipse models; NASA's 2009 edition of its lunar eclipse almanac was based on their values,{{sfn|Espenak|Meeus|2009|p=v}} which effectively reclassified nine eclipses between 1801 and 2300 as non-events, including the one in August 2016.{{efn|The others are: 22 April 1864, 21 June 1872, 26 October 1882, [[February 1951 lunar eclipse|21 February 1951]], [[October 2042 lunar eclipse|28 October 2042]], 7 March 2194, 30 April 2219, and 18 February 2288.|name=|group=}}{{sfn|Espenak|Meeus|2009|p=10}}

Some resources, including the [[HM Nautical Almanac Office]]'s online canon of eclipses, continued to list the 18 August 2016 event. Despite not appearing in NASA's printed lists of eclipses since the 2009 revision, [[AccuWeather]] reported the upcoming eclipse and projected this was the final member of [[Lunar Saros 109]].<ref name="Sutherland" />

== Visibility ==
The eclipse was completely visible over [[Australia]], [[North America|North]] and [[South America]], and [[Antarctica]], seen rising over western Australia and [[northeast Asia]] and setting over eastern North and South America.<ref>{{cite web|title=III. Penumbral Eclipse of the Moon|url=https://aa.usno.navy.mil/downloads/eclipses/L2016Aug18.pdf|publisher=HM Nautical Almanac Office|access-date=16 November 2024}}</ref>

{| class=wikitable width=480
|[[File:Lunar eclipse from moon-2016Aug18.png|315px]]
|[[File:Lunar eclipse chart close-2016Aug18.png|315px]] Hourly motion shown right to left
|}

== Eclipse season ==
{{See also|Eclipse cycle}}
This eclipse is part of an [[eclipse season]], a period, roughly every six months, when eclipses occur. Only two (or occasionally three) eclipse seasons occur each year, and each season lasts about 35 days and repeats just short of six months (173 days) later; thus two full eclipse seasons always occur each year. Either two or three eclipses happen each eclipse season. In the sequence below, each eclipse is separated by a [[fortnight]]. The first and last eclipse in this sequence is separated by one [[month#Synodic_month|synodic month]].

{| class="wikitable"
|+ Eclipse season of August–September 2016
! [[August 2016 lunar eclipse|August 18]] Descending node (full moon) !! [[Solar eclipse of September 1, 2016|September 1]] Ascending node (new moon) !! [[September 2016 lunar eclipse|September 16]] Descending node (full moon) 
|-
| [[File:Lunar eclipse chart close-2016Aug18.png|200px]] || [[File:SE2016Sep01A.png|200px]] || [[File:Lunar eclipse chart close-2016Sep16.png|200px]]
|- align=center
| [[Lunar eclipse#Types of lunar eclipse|Penumbral lunar eclipse]] Lunar Saros 109 || [[Total eclipse#Types|Annular solar eclipse]] Solar Saros 135 || [[Lunar eclipse#Types of lunar eclipse|Penumbral lunar eclipse]] Lunar Saros 147
|}

== Related eclipses ==
=== Eclipses in 2016 ===
* [[Solar eclipse of March 9, 2016|A total solar eclipse on March 9]].
* [[March 2016 lunar eclipse|A penumbral lunar eclipse on March 23]].
* '''A penumbral lunar eclipse on August 18.'''
* [[Solar eclipse of September 1, 2016|An annular solar eclipse on September 1]].
* [[September 2016 lunar eclipse|A penumbral lunar eclipse on September 16]].

=== Metonic ===
* Followed by: [[June 2020 lunar eclipse|Lunar eclipse of June 5, 2020]]

=== Tzolkinex ===
* Preceded by: [[July 2009 lunar eclipse|Lunar eclipse of July 7, 2009]]

=== Tritos ===
* Followed by: [[July 2027 lunar eclipse|Lunar eclipse of July 18, 2027]]

=== Lunar Saros 109 ===
* Preceded by: [[August 1998 lunar eclipse|Lunar eclipse of August 8, 1998]]

=== Inex ===
* Preceded by: [[April 1987 lunar eclipse|Lunar eclipse of April 14, 1987]]
* Followed by: [[March 2045 lunar eclipse|Lunar eclipse of March 3, 2045]]

=== Triad ===
* Followed by: [[June 2103 lunar eclipse|Lunar eclipse of June 20, 2103]]

=== Lunar eclipses of 2016–2020 ===
{{Lunar eclipse set 2016-2020}}

=== Saros 109 ===
{{Lunar Saros series 109}}

=== Inex series ===
{{Inex eclipse set info}}

{| class="wikitable mw-collapsible mw-collapsed"
!colspan=6| Series members between 1801 and 2200
|-
|colspan=2 style="text-align:center;"| [[January 1814 lunar eclipse|1814 Jan 06]] (Saros 102)
|colspan=2 style="text-align:center;"| [[December 1842 lunar eclipse|1842 Dec 17]] (Saros 103)
|colspan=2 style="text-align:center;"|
|-
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|colspan=2 style="text-align:center;"|
|colspan=2 style="text-align:center;"|
|colspan=2 style="text-align:center;"|
|-
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|-
|colspan=2 style="text-align:center;"|
|colspan=2 style="text-align:center;"| [[August 2016 lunar eclipse|2016 Aug 18]] (Saros 109)
|colspan=2 style="text-align:center;"|
|-
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|[[File:Lunar eclipse chart close-2016Aug18.png|80px]]
|[[File:Lunar eclipse from moon-2016Aug18.png|80px]]
|
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|-
|colspan=2 style="text-align:center;"| [[July 2074 lunar eclipse|2074 Jul 08]] (Saros 111)
|colspan=2 style="text-align:center;"| [[June 2103 lunar eclipse|2103 Jun 20]] (Saros 112)
|colspan=2 style="text-align:center;"| [[May 2132 lunar eclipse|2132 May 30]] (Saros 113)
|-
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|-
|colspan=2 style="text-align:center;"| [[May 2161 lunar eclipse|2161 May 09]] (Saros 114)
|colspan=2 style="text-align:center;"| [[April 2190 lunar eclipse|2190 Apr 20]] (Saros 115)
|-
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|}

== See also ==
* [[List of lunar eclipses]]
* [[List of 21st-century lunar eclipses]]
*[[October 2042 lunar eclipse]]
*[[July 2027 lunar eclipse]]

== Notes ==
{{notelist}}

== References ==
{{reflist|1=30em|refs=
<ref name="HMNAO">{{cite web |title=Penumbral Eclipse of the Moon: 2016 August 18 |work=Canon of Eclipses |publisher=HM Nautical Almanac Office |date=22 June 2018 |access-date=11 January 2019 |url=http://astro.ukho.gov.uk/eclipse/1332016/ |archive-date=31 October 2018 |archive-url=https://web.archive.org/web/20181031010347/http://astro.ukho.gov.uk/eclipse/1332016/ |url-status=dead }}</ref>
<ref name="NEWS">{{cite web |title=Catalog of Lunar Eclipse Saros Series: Saros Series 109 |website=NASA Eclipse Web Site |url=https://eclipse.gsfc.nasa.gov/LEsaros/LEsaros109.html |access-date=11 January 2019}}</ref>
<ref name="Sutherland">{{cite web |last=Sutherland |first=Scott |title=An 'almost, maybe' lunar eclipse this week? |publisher=The Weather Network |date=17 August 2016 |access-date=10 January 2019 |url=https://www.theweathernetwork.com/news/articles/whats-visible-in-the-night-sky-this-week-find-out-here-aug-15-21/71166}}</ref>
}}

== Bibliography ==
* {{cite book |last=Espenak |first=Fred |title=Fifty Year Canon of Lunar Eclipses: 1986–2035 |year=1989 |publisher=NASA |id=NASA Reference Publication 1216 |url=https://eclipse.gsfc.nasa.gov/SEpubs/FiftyYearCanonOfLunarEclipses1986-2035_NASA1216_19900009026.pdf }}
* {{cite book |last1=Espenak |first1=Fred |last2=Meeus |first2=Jean |title=Five Millennium Catalog of Lunar Eclipses: -1999 to +3000 (2000 BCE to 3000 CE) |year=2009 |publisher=NASA |id=NASA/TP-2009-213173 |url=https://eclipse.gsfc.nasa.gov/5MCLE/5MKLE-214173.pdf }}

{{Lunar eclipses}}

{{DEFAULTSORT:Lunar eclipse 2016-08}}
[[Category:21st-century lunar eclipses|2016-08]]
[[Category:2016 in science]]
[[Category:August 2016]]

August 2016 lunar eclipse - Revision history

imported>Weatherman4064: /* Related eclipses */