Editing Lunar phase (section)

==Phases of the Moon==
{{Redirect|Waxing gibbous|the album|Waxing Gibbous}}
{{Redirect|Last quarter|the manga series|Last Quarter}}
[[File:Moon phases en.jpg|450px|thumb|left|The phases of the Moon as viewed looking southward from the [[Northern Hemisphere]]. Each phase would be rotated 180° if seen looking northward from the [[Southern Hemisphere]]. The upper part of the diagram is not to scale, as the Moon, the  Earth, and the Moon's orbit are all much smaller relative to the Earth's orbit than shown here.]]

There are four ''principal'' (primary, or major) lunar phases: the [[new moon]], first quarter, [[full moon]], and last quarter (also known as third or final quarter), when the Moon's [[ecliptic longitude]] is at an angle to the Sun (as viewed from the center of the Earth) of 0°, 90°, 180°, and 270° respectively.{{sfn|Seidelmann|1992|p=478}}{{efn|The quarter phases happen when the observer–Moon–Sun angle is 90°{{citation needed|date=December 2022}}, also known as [[quadrature (astronomy)| quadrature]]{{dubious|date=December 2022}}. This is not the same as a [[right angle]]{{dubious|date=December 2022|reason=a right angle is definitely 90°. An observer–Moon–Sun angle of 90° is [[dichotomy]] not quadrature. [[Quadrature (astronomy)]] is when the sun-observer-moon angle is 90°. Also this contradicts the next section which says a quarter moon starts at 50.1% lit, while this description of dichotomy is describing the moon as exactly 50% lit}}, but the difference is very slight. /}} Each of these phases appears at slightly different times at different locations on Earth, and tabulated times are therefore always ''geocentric'' (calculated for the Earth's center).

Between the principal phases are ''intermediate'' phases, during which the apparent shape of the illuminated Moon is either [[crescent]] or [[wikt: gibbous|gibbous]]. On average, the intermediate phases last one-quarter of a [[synodic month]], or 7.38 days.{{efn|Their durations [[orbital eccentricity |vary slightly]] because the [[orbit of the Moon| Moon's orbit]] is somewhat [[elliptic orbit| elliptical]], so its [[orbital speed]] is not constant.}}

The term ''{{linktext|waxing}}'' is used for an intermediate phase when the Moon's apparent shape is thickening, from new to a full moon; and ''{{linktext|waning}}'' when the shape is thinning. The duration from full moon to new moon (or new moon to full moon) varies from approximately {{nowrap|13 days {{frac|22|1|2}} hours}} to about {{nowrap|15 days {{frac|14|1|2}} hours}}.

Due to lunar motion relative to the meridian and the [[ecliptic]], in Earth's [[northern hemisphere]]:
*A new moon appears highest at the summer [[solstice]] and lowest at the winter solstice.
*A first-quarter moon appears highest at the spring [[equinox]] and lowest at the autumn equinox.
*A full moon appears highest at the winter solstice and lowest at the summer solstice.
*A last-quarter moon appears highest at the autumn equinox and lowest at the spring equinox.

Non-Western cultures may use a different number of lunar phases; for example, traditional [[Hawaiian culture]] has a total of 30 phases (one per day).<ref>
{{cite web |title=Hawaiian Moon Names |url=http://www.imiloahawaii.org/57/ |url-status=dead |archive-url= https://web.archive.org/web/20140102085746/http://www.imiloahawaii.org/57 |archive-date= 2014-01-02 |access-date=2013-07-08 |work=Imiloa, Hilo Attractions |language=en}}</ref>
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=== Waxing and waning ===
[[File:The Moon's Phases as Seen from Space.ogv|thumb|left|This video provides an illustration of how the Moon passes through its phases &ndash; a product of its orbit, which allows different parts of its surface to be illuminated by the Sun over the course of a month. The camera is locked to the Moon as Earth rapidly rotates in the foreground.]]
[[File:Moon Phase Diagram for Simple English Wikipedia.GIF|thumb|right|Diagram of the Moon's phases: The Earth is at the center of the diagram and the Moon is shown orbiting.]]
When the Sun and Moon are [[conjunction (astronomy)|aligned on the same side]] of the Earth (conjunct), the Moon is "new", and the side of the Moon facing Earth is not illuminated by the Sun. As the Moon ''waxes'' (the amount of illuminated surface as seen from Earth increases), the lunar phases progress through the new moon, crescent moon, first-quarter moon, [[wikt:gibbous|gibbous]] moon, and full moon phases. The Moon then ''wanes'' as it passes through the gibbous moon, third-quarter moon, and crescent moon phases, before returning back to new moon.

The terms ''old moon'' and ''new moon'' are not interchangeable. The "old moon" is a waning sliver (which eventually becomes undetectable to the naked eye) until the moment it aligns with the Sun and begins to wax, at which point it becomes new again.<ref>{{cite web |title=Free Astronomy Lesson 7 - The Phases of the Moon |url=http://www.synapses.co.uk/astro/moon2.html |access-date=2015-12-28 |archive-url=https://web.archive.org/web/20230414073024/http://www.synapses.co.uk/astro/moon2.html |archive-date=2023-04-14 |url-status=live}}</ref> ''Half moon'' is often used to mean the first- and third-quarter moons, while the term ''quarter'' refers to the extent of the Moon's cycle around the Earth, not its shape.

When an illuminated hemisphere is viewed from a certain angle, the portion of the illuminated area that is visible will have a two-dimensional shape as defined by the intersection of an [[ellipse]] and circle (in which the ellipse's [[major axis]] coincides with the circle's diameter). If the half-ellipse is convex with respect to the half-circle, then the shape will be gibbous (bulging outwards),<ref>{{cite web |title=Gibbous Definition & Meaning |url=https://www.dictionary.com/browse/gibbous |website=[[Dictionary.com]] |archive-url=https://web.archive.org/web/20230421145830/https://www.dictionary.com/browse/gibbous |archive-date=2023-04-21 |language=en |quote=Origin of gibbous: 1350–1400; Middle English <Latin gibbōsus humped, equivalent to gibb(a) hump + -ōsus-ous |url-status=live}}</ref> whereas if the half-ellipse is concave with respect to the half-circle, then the shape will be a [[crescent]]. When a crescent moon occurs, the phenomenon of [[earthlight (astronomy)|earthshine]] may be apparent, where the night side of the Moon dimly reflects indirect sunlight reflected from Earth.{{sfn|Asmelash|Allan|2019|}}
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=== Principal and intermediate phases of the Moon ===
{|class="wikitable"
|-
!scope="col" rowspan="2" colspan="2"| Moon phases
!scope="col" colspan="2"| Illuminated portion
!scope="col" rowspan="2"| Visibility
!scope="col" rowspan="2"| Average<br /> moonrise<br /> time{{efn|name=rise|As with sunrise and sunset, there are seasonal variations in the time of moonrise and moonset.}}
!scope="col" rowspan="2"| [[Culmination]]<br /> time<br /> (highest point)
!scope="col" rowspan="2"| Average<br /> moonset<br /> time{{efn|name=rise}}
!scope="col" colspan="2"| Illustrations from
!scope="col" rowspan="2"| Photograph<br /> (view from the<br /> Northern Hemisphere)
|-
!scope="col"| [[Northern Hemisphere|Northern<br /> Hemisphere]]
!scope="col"| [[Southern Hemisphere|Southern<br /> Hemisphere]]
!scope="col"| [[North Pole|North<br /> Pole]]
!scope="col"| [[South Pole|South<br /> Pole]]
|-id="newmoon"
!scope="row" colspan="2"| [[New Moon]]
|colspan="2" style="text-align:center"| Disc completely in shade<br /> (lit by [[earthshine]] only)
| Invisible (too close to Sun),<br /> except during a total or annular [[solar eclipse]]<br />(when the Moon obscures the Sun disc)
|style="text-align:center"| 06:00 ||style="text-align:center"| 12:00 ||style="text-align:center"| 18:00
|colspan="2" style="text-align:center"| [[File:Moon phase 0.svg|70px]]
|style="text-align:center"| [[File:New Moon.jpg|150px]]
|-id="waxingcrescent"
!scope="row" rowspan="3"| Waxing<br /> moon
!scope="row"| Waxing<br/> [[crescent]]
| Right side:<br /> (1%–49%) lit disc || Left side:<br /> (1%–49%) lit disc
| Late morning to post-dusk
|style="text-align:center"| 09:00 ||style="text-align:center"| 15:00 ||style="text-align:center"| 21:00
|style="text-align:center"| [[File:Moon phase 1.svg|70px]]
|style="text-align:center"| [[File:Moon phase 7.svg|70px]]
|style="text-align:center"| [[File:Waxing Crescent Moon on 4-1-17 (33627493622).jpg|150px]]
|-id="firstquarter"
!scope="row"| First<br/> quarter
| Right side:<br /> 50% lit disc || Left side:<br /> 50% lit disc
| Afternoon and early night
|style="text-align:center"| 12:00 ||style="text-align:center"| 18:00 ||style="text-align:center"| 00:00
|style="text-align:center"| [[File:Moon phase 2.svg|70px]]
|style="text-align:center"| [[File:Moon phase 6.svg|70px]]
|style="text-align:center"| [[File:Daniel Hershman - march moon (by).jpg|150px]]
|-id="waxinggibbous"
!scope="row"| Waxing<br/> gibbous
| Right side:<br /> (51%–99%) lit disc || Left side:<br /> (51%–99%) lit disc
| Late afternoon and most of night
|style="text-align:center"| 15:00 ||style="text-align:center"| 21:00 ||style="text-align:center"| 03:00
|style="text-align:center"| [[File:Moon phase 3.svg|70px]]
|style="text-align:center"| [[File:Moon phase 5.svg|70px]]
|style="text-align:center"| [[File:Lune-Nikon-600-F4 Luc Viatour.jpg|150px]]
|-id="fullmoon"
!scope="row" colspan="2"| [[Full Moon]]
|colspan="2" style="text-align:center"| 100% illuminated disc,<br /> except during a total or partial [[lunar eclipse]]<br />(when the Moon crosses the Earth's shadow)
| Sunset to sunrise (all night)
|style="text-align:center"| 18:00 ||style="text-align:center"| 00:00 ||style="text-align:center"| 06:00
|colspan="2" style="text-align:center"| [[File:Moon phase 4.svg|70px]]
|style="text-align:center"| [[File:20110319 Supermoon.jpg|150px]]
|-id="waninggibbous"
!scope="row" rowspan="3"| Waning<br /> moon
!scope="row"| Waning<br/> gibbous
| Left side:<br /> (99%–51%) lit disc || Right side:<br /> (99%–51%) lit disc
| Most of night and early morning
|style="text-align:center"| 21:00 ||style="text-align:center"| 03:00 ||style="text-align:center"| 09:00
|style="text-align:center"| [[File:Moon phase 5.svg|70px]]
|style="text-align:center"| [[File:Moon phase 3.svg|70px]]
|style="text-align:center"| [[File:2013-01-02 00-00-55-Waning-gibbous-moon.jpg|150px]]
|-id="lastquarter"
!scope="row"| Last<br/> quarter
| Left side:<br /> 50% lit disc || Right side:<br /> 50% lit disc
| Late night and morning
|style="text-align:center"| 00:00 ||style="text-align:center"| 06:00 ||style="text-align:center"| 12:00
|style="text-align:center"| [[File:Moon phase 6.svg|70px]]
|style="text-align:center"| [[File:Moon phase 2.svg|70px]]
|style="text-align:center"| [[File:Waning gibbous moon near last quarter - 23 Sept. 2016.png|150px]]
|-id="waningcrescent"
!scope="row"| Waning<br/> crescent
| Left side:<br /> (49%–1%) lit disc || Right side:<br /> (49%–1%) lit disc
| Pre-dawn to early afternoon
|style="text-align:center"| 03:00 ||style="text-align:center"| 09:00 ||style="text-align:center"| 15:00
|style="text-align:center"| [[File:Moon phase 7.svg|70px]]
|style="text-align:center"| [[File:Moon phase 1.svg|70px]]
|style="text-align:center"| [[File:Waning Crescent Moon(7Sep15).jpg|150px]]
|}