View source for Solar eclipse

{{short description|Natural phenomenon wherein the Sun is obscured by the Moon}}
{{About||the video game|Solar Eclipse (video game){{!}}''Solar Eclipse'' (video game)|the song|Solar Eclipse (song)}}
{{redirect|Eclipse of the Sun|other uses|Eclipse of the Sun (disambiguation)}}
{{pp-vandalism|small=yes}}
{{Infobox
| image            = [[File:Solar eclipse 1999 4.jpg|300px|Total solar eclipse]]
| caption          = A ''total solar eclipse'' occurs when the Moon completely covers the Sun's disk. [[Solar prominence]]s can be seen along the limb (in red) as well as extensively the [[solar corona|coronal]] and partly the radiating [[coronal streamer]]s. ([[Solar eclipse of August 11, 1999|August 11, 1999]])
| image2           = [[File:2023 Annual Eclipse.jpg|300px|Annular solar eclipse]]
| caption2         = An ''annular solar eclipse'' occurs when the Moon is too far away to completely cover the Sun's disk ([[Solar eclipse of October 14, 2023|October 14, 2023]]).
| image3           = [[File:Sun eclipse 25 oct 2022 in Saratov.jpg|200px|Partial solar eclipse]]
| caption3         = During a ''partial solar eclipse'', the Moon blocks only part of the Sun's disk ([[Solar eclipse of October 25, 2022|October 25, 2022]]).
}}

A '''solar eclipse''' occurs when the [[Moon]] passes between [[Earth]] and the [[Sun]], thereby obscuring the view of the Sun from a small part of Earth, totally or partially. Such an alignment occurs approximately every six months, during the [[eclipse season]] in its [[new moon]] phase, when the Moon's orbital plane is closest to [[Ecliptic|the plane of Earth's orbit]].<ref>{{Cite news|url=https://www.esa.int/Our_Activities/Space_Science/What_is_an_eclipse|title=What is an eclipse?|work=European Space Agency|access-date=2018-08-04|archive-date=2018-08-04|archive-url=https://web.archive.org/web/20180804140739/https://www.esa.int/Our_Activities/Space_Science/What_is_an_eclipse|url-status=live}}</ref> In a total [[eclipse]], the disk of the Sun is fully obscured by the Moon. In [[#Types|partial and annular eclipses]], only part of the Sun is obscured. Unlike a [[lunar eclipse]], which may be viewed from anywhere on the [[night]] side of Earth, a solar eclipse can only be viewed from a relatively small area of the world. As such, although total solar eclipses occur somewhere on Earth every 18 months on average, they recur at any given place only once every 360 to 410 years.

If the Moon were in a perfectly circular orbit and in the same orbital plane as Earth, there would be total solar eclipses once a month, at every new moon. Instead, because the Moon's orbit is [[inclination|tilted]] at about 5 degrees to Earth's orbit, its shadow usually misses Earth. Solar (and lunar) eclipses therefore happen only during [[eclipse season]]s, resulting in at least two, and up to five, solar eclipses each year, no more than two of which can be total.<ref name="totality">{{Cite book |last1=Littmann |first1=Mark |title=Totality: Eclipses of the Sun |last2=Espenak |first2=Fred |last3=Willcox |first3=Ken |date=2008 |publisher=Oxford University Press |isbn=978-0-19-953209-4 |pages=18–19}}</ref><ref>Five solar eclipses occurred in 1935.{{Cite book |author=NASA |url=http://eclipse.gsfc.nasa.gov/eclipse.html |title=NASA Eclipse Web Site |date=September 6, 2009 |others=[[Fred Espenak]], Project and Website Manager |chapter=Five Millennium Catalog of Solar Eclipses |author-link=NASA |access-date=January 26, 2010 |chapter-url=http://eclipse.gsfc.nasa.gov/SEcat5/SE1901-2000.html |archive-url=https://web.archive.org/web/20100429001425/http://eclipse.gsfc.nasa.gov/eclipse.html |archive-date=April 29, 2010 |url-status=live}}</ref> Total eclipses are rarer because they require a more precise alignment between the centers of the [[Sun]] and [[Moon]], and because the Moon's [[Angular diameter|apparent size]] in the sky is sometimes too small to fully cover the Sun.

An eclipse is a [[List of natural phenomena|natural phenomenon]]. In some ancient and modern cultures, solar eclipses were attributed to [[supernatural]] causes or regarded as bad [[omen]]s. Astronomers' predictions of eclipses began in China as early as the 4th century BC; eclipses hundreds of years into the future may now be predicted with high accuracy. 

[[Sungazing|Looking directly at the Sun]] can lead to permanent eye damage, so special eye protection or indirect viewing techniques are used when viewing a solar eclipse. Only the total phase of a total solar eclipse is safe to view without protection. Enthusiasts known as [[Eclipse chasing|eclipse chasers]] or umbraphiles travel to remote locations to see solar eclipses.<ref>{{cite news |last=Koukkos |first=Christina |title=Eclipse Chasing, in Pursuit of Total Awe |url=https://www.nytimes.com/2009/05/17/travel/17journeys.html |work=The New York Times |date=May 14, 2009|access-date=January 15, 2012 |archive-date=June 26, 2018 |archive-url=https://web.archive.org/web/20180626220600/https://www.nytimes.com/2009/05/17/travel/17journeys.html|url-status=live}}</ref><ref>{{cite news|url=https://www.nytimes.com/2010/07/11/opinion/11pasachoff.html|title=Why I Never Miss a Solar Eclipse|last=Pasachoff|first=Jay M.|work=The New York Times|date=July 10, 2010|access-date=January 15, 2012|archive-date=June 26, 2018|archive-url=https://web.archive.org/web/20180626220540/https://www.nytimes.com/2010/07/11/opinion/11pasachoff.html|url-status=live}}</ref>

== Types ==
[[File:Solar Eclipse May 20,2012.jpg|thumb|Partial and annular phases of the [[solar eclipse of May 20, 2012]]]]

The Sun's distance from Earth is about 400 times the Moon's distance, and the Sun's [[diameter]] is about 400 times the Moon's diameter. Because these ratios are approximately the same, the Sun and the Moon as seen from Earth appear to be approximately the same size: about 0.5 [[degree of arc]] in angular measure.<ref name="Harrington10"/>

The Moon's orbit around Earth is slightly [[ellipse|elliptical]], as is Earth's orbit around the Sun. The apparent sizes of the Sun and Moon therefore vary.<ref>{{cite web |title=Solar Eclipses |website=University of Tennessee |url=http://csep10.phys.utk.edu/astr161/lect/time/eclipses.html |access-date=January 15, 2012 |archive-date=June 9, 2015 |archive-url=https://web.archive.org/web/20150609061419/http://csep10.phys.utk.edu/astr161/lect/time/eclipses.html |url-status=live }}</ref> The [[magnitude of an eclipse]] is the ratio of the apparent size of the Moon to the apparent size of the Sun during an eclipse. An eclipse that occurs when the Moon is near its closest distance to Earth (''i.e.,'' near its [[perigee]]) can be a total eclipse because the Moon will appear to be large enough to completely cover the Sun's bright disk or [[photosphere]]; a total eclipse has a magnitude greater than or equal to 1.000. Conversely, an eclipse that occurs when the Moon is near its farthest distance from Earth (''i.e.,'' near its [[apogee]]) can be only an annular eclipse because the Moon will appear to be slightly smaller than the Sun; the magnitude of an annular eclipse is less than 1.<ref>{{cite web|url=https://spaceplace.nasa.gov/total-solar-eclipse/en/|title=How Is the Sun Completely Blocked in an Eclipse?|publisher=[[NASA]]|work=NASA Space Place|date=2009|access-date=2019-09-01|archive-date=2021-01-19|archive-url=https://web.archive.org/web/20210119144036/https://spaceplace.nasa.gov/total-solar-eclipse/en/|url-status=live}}</ref>

Because Earth's orbit around the Sun is also elliptical, Earth's distance from the Sun similarly varies throughout the year. This affects the apparent size of the Sun in the same way, but not as much as does the Moon's varying distance from Earth.<ref name="Harrington10"/> When Earth approaches its [[Aphelion|farthest distance from the Sun]] in early July, a total eclipse is somewhat more likely, whereas conditions favour an annular eclipse when Earth approaches its [[perihelion|closest distance to the Sun]] in early January.<ref>Steel, p. 351</ref>

There are three main types of solar eclipses:<ref name="Baylor2024">{{cite web |url=https://eclipse.web.baylor.edu/what-is-an-eclipse |title=What is a solar eclipse? |author=Baylor University Department of Physics |publisher=Baylor University |date=2024 |access-date=April 12, 2024 |quote=There are three main types of solar eclipses: Total solar eclipse, Partial solar eclipse, Annular solar eclipse}}</ref>

===Total eclipse===

A total eclipse occurs on average every 18 months<ref name=":0" /> when the dark silhouette of the Moon completely obscures the bright light of the Sun, allowing the much fainter [[solar corona]] to be visible. During an eclipse, totality occurs only along a narrow track on the surface of Earth.<ref>Harrington, pp. 7–8</ref> This narrow track is called the path of totality.<ref>{{Cite web|url=https://eclipse2017.nasa.gov/eclipse-who-what-where-when-and-how|title=Eclipse: Who? What? Where? When? and How? {{!}} Total Solar Eclipse 2017|website=eclipse2017.nasa.gov|language=en|access-date=2017-09-21|archive-url=https://web.archive.org/web/20170918131433/https://eclipse2017.nasa.gov/eclipse-who-what-where-when-and-how|archive-date=2017-09-18}}</ref>

===Annular eclipse===

An annular eclipse, like a total eclipse, occurs when the Sun and Moon are exactly in line with Earth. During an annular eclipse, however, the apparent size of the Moon is not large enough to completely block out the Sun.<ref name="Harrington10">Harrington, pp. 9–11</ref> Totality thus does not occur; the Sun instead appears as a very bright ring, or [[annulus (mathematics)|annulus]], surrounding the dark disk of the Moon.<ref name="Harrington10">Harrington, pp. 9–11</ref> Annular eclipses occur once every one or two years, not annually.<ref name=":0">{{Cite web |title=What Are the Three Types of Solar Eclipses? |url=https://www.exploratorium.edu/eclipse/three-kinds-solar-eclipses |access-date=11 Oct 2023 |website=Exploratorium|date=17 April 2023 }}</ref><ref name="EclipseAnnularAnnual"/> The term derives from the [[Latin]] [[root word]] ''[[wiktionary:anulus#Latin|anulus]]'', meaning "ring", rather than ''[[wiktionary:annus#Latin|annus]]'', for "year".<ref name="EclipseAnnularAnnual">{{cite news |last=Villalpando |first=Roberto |date=September 15, 2023 |title=October eclipse will be annular, not annual, but oversized glasses show how confusing it can be |url=https://www.expressnews.com/san-antonio-weather/article/eclipse-glasses-display-see-annular-annual-18368477.php |work=[[San Antonio Express-News]] |access-date=April 11, 2024 |quote=Annular means of, relating to or forming a ring [...] it has its roots in the Latin word for ring, 'anulus'. [...] Annual, on the other hand, means occurring every year or once a year. The word also has a Latin ancestor: 'annus', which means year.}}</ref>

===Partial eclipse===

A partial eclipse occurs about twice a year,<ref name=":0" /> when the Sun and Moon are not exactly in line with Earth and the Moon only partially obscures the Sun. This phenomenon can usually be seen from a large part of Earth outside of the track of an annular or total eclipse. However, some eclipses can be seen only as a partial eclipse, because the [[umbra]] passes above Earth's polar regions and never intersects Earth's surface.<ref name="Harrington10"/> Partial eclipses are virtually unnoticeable in terms of the Sun's brightness, as it takes well over 90% coverage to notice any darkening at all. Even at 99%, it would be no darker than [[civil twilight]].<ref>{{cite web|title=Transit of Venus, Sun–Earth Day 2012|website=nasa.gov|url=http://sunearthday.nasa.gov/2012/facts.php|access-date=February 7, 2016|archive-date=January 14, 2016|archive-url=https://web.archive.org/web/20160114081913/http://sunearthday.nasa.gov/2012/facts.php|url-status=live}}</ref>

[[File:Comparison angular diameter.svg|thumb|Comparison of minimum and maximum apparent sizes of the Sun and Moon (and planets). An annular eclipse can occur when the Sun has a larger apparent size than the Moon, whereas a total eclipse can occur when the Moon has a larger apparent size.]]

==Terminology==

===Hybrid eclipse===

A hybrid eclipse (also called annular/total eclipse) shifts between a total and annular eclipse. At certain points on the surface of Earth, it appears as a total eclipse, whereas at other points it appears as annular. Hybrid eclipses are comparatively rare.<ref name="Harrington10"/>

A hybrid eclipse occurs when the magnitude of an eclipse changes during the event from less to greater than one, so the eclipse appears to be total at locations nearer the midpoint, and annular at other locations nearer the beginning and end, since the sides of Earth are slightly further away from the Moon.  These eclipses are extremely narrow in their path width and relatively short in their duration at any point compared with fully total eclipses; the [[Solar eclipse of April 20, 2023|2023 April 20 hybrid eclipse]]'s totality is over a minute in duration at various points along the path of totality.  Like a [[focus (optics)|focal point]], the width and duration of totality and annularity are near zero at the points where the changes between the two occur.<ref>{{cite web|first=Fred|last=Espenak|date=September 26, 2009|title=Solar Eclipses for Beginners|url=http://www.mreclipse.com/Special/SEprimer.html|access-date=January 15, 2012|website=MrEclipse.com|archive-date=May 24, 2015|archive-url=https://web.archive.org/web/20150524172606/http://www.mreclipse.com/Special/SEprimer.html|url-status=live}}</ref>

===Central eclipse===
{{multiple image
| align     = right
| direction = horizontal
| image1    = Solar eclipse visualisation.svg
| width1    = 250
| caption1  = Each icon shows the view from the centre of its black spot, representing the Moon (not to scale)
| image2    = Exit Diamond Ring Effect.jpg
| width2    = 200
| caption2  = Diamond ring effect at third contact—the end of totality—with visible prominences ([[Solar eclipse of August 21, 2017|August 21, 2017]])
}}
''Central eclipse'' is often used as a generic term for a total, annular, or hybrid eclipse.<ref name="SEpath">{{cite web|url=http://eclipse.gsfc.nasa.gov/SEpath/SEpath.html|title=Central Solar Eclipses: 1991–2050|first=Fred|last=Espenak|date=January 6, 2009|publisher=NASA Goddard Space Flight Center|work=NASA Eclipse web site|location=Greenbelt, MD|access-date=January 15, 2012|archive-date=January 8, 2021|archive-url=https://web.archive.org/web/20210108223913/https://eclipse.gsfc.nasa.gov/SEpath/SEpath.html|url-status=live}}</ref> This is, however, not completely correct: the definition of a central eclipse is an eclipse during which the central line of the umbra touches Earth's surface. It is possible, though extremely rare, that part of the umbra intersects with Earth (thus creating an annular or total eclipse), but not its central line. This is then called a non-central total or annular eclipse.<ref name="SEpath"/> [[Gamma (eclipse)|Gamma]] is a measure of how centrally the shadow strikes. The last (umbral yet) non-central solar eclipse was [[Solar eclipse of April 29, 2014|on April 29, 2014]]. This was an annular eclipse. The next non-central total solar eclipse will be [[Solar eclipse of April 9, 2043|on April 9, 2043]].{{Update after|2043|4|8}}<ref>{{cite web|first=Felix|last=Verbelen|title=Solar Eclipses on Earth, 1001 BC to AD 2500|date=November 2003|url=http://users.online.be/felixverbelen/catzeute.htm|access-date=January 15, 2012|website=online.be|archive-date=August 3, 2019|archive-url=https://web.archive.org/web/20190803210722/http://users.online.be/felixverbelen/catzeute.htm|url-status=live}}</ref>

===Eclipse phases===

The visual phases observed during a total eclipse are called:<ref>Harrington, pp. 13–14; Steel, pp. 266–279</ref>
* First contact—when the Moon's limb (edge) is exactly tangential to the Sun's limb.
* Second contact—starting with [[Baily's Beads]] (caused by light shining through valleys on the Moon's surface) and the [[diamond ring effect]]. Almost the entire disk is covered.
* Totality—the Moon obscures the entire disk of the Sun and only the [[Stellar corona|solar corona]] is visible.
* Third contact—when the first bright light becomes visible and the Moon's shadow is moving away from the observer. Again a diamond ring may be observed.
* Fourth contact—when the trailing edge of the Moon ceases to overlap with the solar disk and the eclipse ends.

==Predictions==

===Geometry===
[[File:Geometry of a Total Solar Eclipse.svg|thumb|300px|right|Geometry of a total solar eclipse (not to scale)]]The diagrams to the right show the alignment of the Sun, Moon, and Earth during a solar eclipse. The dark gray region between the Moon and Earth is the [[umbra]], where the Sun is completely obscured by the Moon. The small area where the umbra touches Earth's surface is where a total eclipse can be seen. The larger light gray area is the [[penumbra]], in which a partial eclipse can be seen. An observer in the [[Umbra#Antumbra|antumbra]], the area of shadow beyond the umbra, will see an annular eclipse.<ref>Mobberley, pp. 30–38</ref>

The [[Orbit of the Moon|Moon's orbit]] around Earth is inclined at an angle of just over 5 degrees to the plane of Earth's orbit around the Sun (the [[ecliptic]]). Because of this, at the time of a new moon, the Moon will usually pass to the north or south of the Sun. A solar eclipse can occur only when a new moon occurs close to one of the points (known as [[Orbital node|nodes]]) where the Moon's orbit crosses the ecliptic.<ref name="Harrington">Harrington, pp. 4–5</ref>

As noted above, the Moon's orbit is also [[ellipse|elliptical]]. The Moon's distance from Earth varies by up to about 5.9% from its average value. Therefore, the Moon's apparent size varies with its distance from Earth, and it is this effect that leads to the difference between total and annular eclipses. The distance of Earth from the Sun also varies during the year, but this is a smaller effect (by up to about 0.85% from its average value). On average, the Moon appears to be slightly (2.1%) smaller than the Sun as seen from Earth, so the majority (about 60%) of central eclipses are annular. It is only when the Moon is closer to Earth than average (near its [[perigee]]) that a total eclipse occurs.<ref>{{cite web|first=Ron|last=Hipschman|title=Why Eclipses Happen|website=Exploratorium|url=http://www.exploratorium.edu/eclipse/why.html|access-date=January 14, 2012|archive-date=December 27, 2015|archive-url=https://web.archive.org/web/20151227052022/http://www.exploratorium.edu/eclipse/why.html|url-status=live}}</ref><ref>{{cite web|author=Brewer, Bryan|date=January 14, 1998|title=What Causes an Eclipse?|website=Earth View|url=http://www.earthview.com/tutorial/causes.htm|access-date=January 14, 2012|archive-url=https://archive.today/20130102203300/http://www.earthview.com/tutorial/causes.htm|archive-date=January 2, 2013}}</ref>

{| class="wikitable" style="text-align:center"
|-
! rowspan="2" |
! colspan="2" | Moon
! colspan="2" | Sun
|-
! width="100" | At perigee<br />(nearest)
! width="100" | At apogee<br />(farthest)
! width="100" | At perihelion<br />(nearest)
! width="100" | At aphelion<br />(farthest)
|-
! Mean radius
| colspan=2 | {{convert|1737.10|km|mi|abbr=on|disp=br()|comma=off}}
| colspan=2 | {{convert|696000|km|mi|abbr=on|disp=br()|comma=gaps}}
|-
! Distance
| {{convert|363104|km|mi|abbr=on|disp=br()|comma=gaps}}
| {{convert|405696|km|mi|abbr=on|disp=br()|comma=gaps}}
| {{convert|147098070|km|mi|abbr=on|disp=br()|comma=gaps}}
| {{convert|152097700|km|mi|abbr=on|disp=br()|comma=gaps}}
|-
! style="line-height: 120%;" | Angular<br />diameter<ref>[http://education.gsfc.nasa.gov/eclipse/pages/faq.html NASA – Eclipse 99 – Frequently Asked Questions] {{webarchive|url=https://web.archive.org/web/20100527142627/http://education.gsfc.nasa.gov/eclipse/pages/faq.html |date=2010-05-27 }} – There is a mistake in the ''How long will we continue to be able to see total eclipses of the Sun?'' answer, "...the Sun's angular diameter varies from 32.7 minutes of arc when the Earth is at its farthest point in its orbit (aphelion), and 31.6 arc minutes when it is at its closest (perihelion)." It should appear smaller when farther, so the values should be swapped.</ref>
| 33' 30"<br />(0.5583°)
| 29' 26"<br />(0.4905°)
| 32' 42"<br />(0.5450°)
| 31' 36"<br />(0.5267°)
|- style="height:110px"
! style="line-height:120%" | Apparent size<br />to scale
| style="background:black" | [[File:-Phase of the moon NO.16.jpg|91px]]
| style="background:black" | [[File:-Phase of the moon NO.16.jpg|80px]]
| style="background:black" | [[File:The Sun by the Atmospheric Imaging Assembly of NASA's Solar Dynamics Observatory - 20100801.jpg|89px]]
| style="background:black" | [[File:The Sun by the Atmospheric Imaging Assembly of NASA's Solar Dynamics Observatory - 20100801.jpg|86px]]
|-
! style="line-height: 120%;" | Order by<br />decreasing<br />apparent size
| 1st
| 4th
| 2nd
| 3rd
|}

The Moon orbits Earth in approximately 27.3 days, relative to a [[Inertial frame of reference|fixed frame of reference]]. This is known as the [[sidereal month]]. However, during one sidereal month, Earth has revolved part way around the Sun, making the average time between one new moon and the next longer than the sidereal month: it is approximately 29.5 days. This is known as the [[synodic month]] and corresponds to what is commonly called the [[lunar month]].<ref name="Harrington"/>

The Moon crosses from south to north of the ecliptic at its [[ascending node]], and vice versa at its descending node.<ref name="Harrington"/> However, the nodes of the Moon's orbit are gradually moving in a [[retrograde motion]], due to the action of the Sun's gravity on the Moon's motion, and they make a complete circuit every 18.6 years. This regression means that the time between each passage of the Moon through the ascending node is slightly shorter than the sidereal month. This period is called the nodical or [[draconic month]].<ref>Steel, pp. 319–321</ref>

Finally, the Moon's perigee is moving forwards or precessing in its orbit and makes a complete circuit in 8.85 years. The time between one perigee and the next is slightly longer than the sidereal month and known as the [[anomalistic month]].<ref>Steel, pp. 317–319</ref>

The Moon's orbit intersects with the ecliptic at the two nodes that are 180 degrees apart. Therefore, the new moon occurs close to the nodes at two periods of the year approximately six months (173.3 days) apart, known as [[eclipse season]]s, and there will always be at least one solar eclipse during these periods. Sometimes the new moon occurs close enough to a node during two consecutive months to eclipse the Sun on both occasions in two partial eclipses. This means that, in any given year, there will always be at least two solar eclipses, and there can be as many as five.<ref>Harrington, pp. 5–7</ref>

Eclipses can occur only when the Sun is within about 15 to 18 degrees of a node, (10 to 12 degrees for central eclipses). This is referred to as an eclipse limit, and is given in ranges because the apparent sizes and speeds of the Sun and Moon vary throughout the year. In the time it takes for the Moon to return to a node (draconic month), the apparent position of the Sun has moved about 29 degrees, relative to the nodes.<ref name="totality" /> Since the eclipse limit creates a window of opportunity of up to 36 degrees (24 degrees for central eclipses), it is possible for partial eclipses (or rarely a partial and a central eclipse) to occur in consecutive months.<ref name="period">{{cite web|url=http://eclipse.gsfc.nasa.gov/SEsaros/SEperiodicity.html|title=Periodicity of Solar Eclipses|first=Fred|last=Espenak|publisher=NASA Goddard Space Flight Center|website=NASA Eclipse web site|location=Greenbelt, MD|date=August 28, 2009|access-date=January 15, 2012|archive-date=November 12, 2020|archive-url=https://web.archive.org/web/20201112015745/https://eclipse.gsfc.nasa.gov/SEsaros/SEperiodicity.html|url-status=live}}</ref><ref>{{cite web|url=http://eclipse.gsfc.nasa.gov/5MCSE/5MCSEcatalog.txt|title=Five Millennium Catalog of Solar Eclipses: -1999 to +3000|author1=Espenak, Fred|author2=Meeus, Jean|publisher=NASA Goddard Space Flight Center|website=NASA Eclipse web site|location=Greenbelt, MD|date=January 26, 2007|access-date=January 15, 2012|archive-date=October 24, 2020|archive-url=https://web.archive.org/web/20201024223753/https://eclipse.gsfc.nasa.gov/5MCSE/5MCSEcatalog.txt|url-status=live}}</ref>

[[File:graph_solar_eclipse_coverage.svg|thumb|Fraction of the Sun's disc covered, ''f'', when the same-sized discs are offset a fraction ''t'' of their diameter.<ref>[[European Space Agency]], "[https://books.google.com/books?id=h0BWxgEACAAJ Spacecraft flight dynamics] {{Webarchive|url=https://web.archive.org/web/20191211124642/https://books.google.com/books?id=h0BWxgEACAAJ |date=2019-12-11 }}: proceedings of an international symposium, 18–22 May 1981 – Darmstadt, Germany", p. 347</ref>]]

===Path===
[[File:An_EPIC_Eclipse.gif|thumb|From space, the Moon's shadow during the [[solar eclipse of March 9, 2016]] appears as a dark spot moving across Earth.]]
During a central eclipse, the Moon's umbra (or antumbra, in the case of an annular eclipse) moves rapidly from west to east across Earth. Earth is also rotating from west to east, at about 28&nbsp;km/min at the Equator, but as the Moon is moving in the same direction as [[Earth's rotation]] at about 61&nbsp;km/min, the umbra almost always appears to move in a roughly west–east direction across a map of Earth at the speed of the Moon's orbital velocity minus Earth's rotational velocity.<ref>Mobberley, pp. 33–37</ref>

The width of the track of a central eclipse varies according to the relative apparent diameters of the Sun and Moon. In the most favourable circumstances, when a total eclipse occurs very close to perigee, the track can be up to {{convert|267|km|abbr=on}} wide and the duration of totality may be over 7 minutes.<ref>{{cite web|title=How do eclipses such as the one on Wednesday 14 November 2012 occur?|website=Sydney Observatory|url=http://www.sydneyobservatory.com.au/2012/how-do-eclipses-such-as-the-one-on-wednesday-14-november-2012-occur/|archive-url=https://web.archive.org/web/20130429030715/http://www.sydneyobservatory.com.au/2012/how-do-eclipses-such-as-the-one-on-wednesday-14-november-2012-occur/|archive-date=29 April 2013|access-date=20 March 2015}}</ref> Outside of the central track, a partial eclipse is seen over a much larger area of Earth. Typically, the umbra is 100–160&nbsp;km wide, while the penumbral diameter is in excess of 6400&nbsp;km.<ref>Steel, pp. 52–53</ref>

[[Besselian elements]] are used to predict whether an eclipse will be partial, annular, or total (or annular/total), and what the eclipse circumstances will be at any given location.<ref name="ExplanatorySupplement3">{{cite book |editor-first1 = P. Kenneth |editor-last1 = Seidelmann |editor-first2 = Sean E. |editor-last2 = Urban |title = Explanatory Supplement to the Astronomical Almanac |edition=3rd |date=2013 |publisher = University Science Books |isbn=978-1-891389-85-6}}</ref>{{rp|Chapter 11}}

Calculations with Besselian elements can determine the exact shape of the umbra's shadow on Earth's surface. But at what ''longitudes'' on Earth's surface the shadow will fall, is a function of Earth's rotation, and on how much that rotation has slowed down over time. A number called [[ΔT (timekeeping)|ΔT]] is used in eclipse prediction to take this slowing into account. As Earth slows, ΔT increases. ΔT for dates in the future can only be roughly estimated because Earth's rotation is slowing irregularly. This means that, although it is possible to predict that there will be a total eclipse on a certain date in the far future, it is not possible to predict in the far future exactly at what longitudes that eclipse will be total. Historical records of eclipses allow estimates of past values of ΔT and so of Earth's rotation.
<ref name="ExplanatorySupplement3" />{{rp|Equation 11.132}}

===Duration===
The following factors determine the duration of a total solar eclipse (in order of decreasing importance):<ref name="longest"/><ref>M. Littman, et al.</ref>
# The Moon being almost exactly at perigee (making its angular diameter as large as possible).
# Earth being very near [[apsis|aphelion]] (furthest away from the Sun in its elliptical orbit, making its angular diameter nearly as small as possible).
# The midpoint of the eclipse being very close to Earth's equator, where the rotational velocity is greatest and is closest to the speed of the lunar shadow moving over Earth's surface.
# The vector of the eclipse path at the midpoint of the eclipse aligning with the vector of Earth's rotation (i.e. not diagonal but due east).
# The midpoint of the eclipse being near the [[subsolar point]] (the part of Earth closest to the Sun).
The longest eclipse that has been calculated thus far is the eclipse of [[Solar eclipse of July 16, 2186|July 16, 2186]] (with a maximum duration of 7 minutes 29 seconds over northern Guyana).<ref name="longest"/>

==Occurrence and cycles==
{{Main|Eclipse cycle}}
[[File:Eclipse vs new or full moons, annotated.svg|thumb|As Earth revolves around the Sun, approximate [[axial parallelism]] of the Moon's orbital plane ([[orbital inclination|tilted]] five degrees to Earth[[ecliptic|'s orbital plane]]) results in the revolution of the [[lunar nodes]] relative to Earth. This causes an [[eclipse season]] approximately every six months, in which a solar eclipse can occur at the [[new moon]] phase and a [[lunar eclipse]] can occur at the [[full moon]] phase.]]

[[File:Total Solar Eclipse Paths- 1001-2000.gif|thumb|330x330px|Total solar eclipse paths: 1001–2000, showing that total solar eclipses occur almost everywhere on Earth. This image was merged from 50 separate images from [[NASA]].<ref>{{cite web|first=Fred|last=Espenak|title=World Atlas of Solar Eclipse Paths|url=http://sunearth.gsfc.nasa.gov/eclipse/SEatlas/SEatlas.html|publisher=NASA Goddard Space Flight Center|website=NASA Eclipse web site|date=March 24, 2008|access-date=January 15, 2012|url-status=dead|archive-url=https://archive.today/20120714123918/http://sunearth.gsfc.nasa.gov/eclipse/SEatlas/SEatlas.html|archive-date=July 14, 2012}}</ref>]]

A total solar eclipse is a rare event, recurring somewhere on Earth every 18 months on average,<ref>Steel, p. 4</ref> yet is estimated to recur at any given location only every 360–410 years on average.<ref>For 360 years, see Harrington, p. 9; for 410 years, see Steel, p. 31</ref> The total eclipse lasts for only a maximum of a few minutes at any location because the Moon's umbra moves eastward at over {{cvt|1700|km/h|mph m/s ft/s|comma=off}}.<ref>Mobberley, pp. 33–36; Steel, p. 258</ref> Totality currently can never last more than 7&nbsp;min 32&nbsp;s. This value changes over the millennia and is currently decreasing. By the 8th millennium, the longest theoretically possible total eclipse will be less than 7&nbsp;min 2&nbsp;s.<ref name="longest">{{cite journal|last=Meeus|first=J.|title=The maximum possible duration of a total solar eclipse|journal=Journal of the British Astronomical Association|date=December 2003|volume=113|issue=6|pages=343–348|bibcode = 2003JBAA..113..343M }}</ref> The last time an eclipse longer than 7 minutes occurred was [[Solar eclipse of June 30, 1973|June 30, 1973]] (7 min 3 sec). [[1973 Eclipse Flight of Concorde 001|Observers aboard a Concorde supersonic aircraft were able to stretch totality for this eclipse to about 74 minutes]] by flying along the path of the Moon's umbra.<ref>{{cite journal|title=Eclipse Flight of Concorde 001 | volume=246 |issue=5428 | doi=10.1038/246072a0|journal=Nature|pages=72–74|bibcode = 1973Natur.246...72B |year=1973 |last1=Beckman |first1=J. |last2=Begot |first2=J. |last3=Charvin |first3=P. |last4=Hall |first4=D. |last5=Lena |first5=P. |last6=Soufflot |first6=A. |last7=Liebenberg |first7=D. |last8=Wraight |first8=P. | s2cid=10644966 }}</ref> The next total eclipse exceeding seven minutes in duration will not occur until [[Solar eclipse of June 25, 2150|June 25, 2150]]. The longest total solar eclipse during the {{gaps|11|000}} year period from 3000 BC to at least 8000 AD will occur on [[Solar eclipse of July 16, 2186|July 16, 2186]], when totality will last 7&nbsp;min 29&nbsp;s.<ref name="longest" /><ref>{{Cite book|first=F. Richard|last=Stephenson|title=Historical Eclipses and Earth's Rotation|publisher=Cambridge University Press|date=1997|page=54|isbn=0-521-46194-4|doi=10.1017/CBO9780511525186|url=http://ebooks.cambridge.org/ebook.jsf?bid=CBO9780511525186|access-date=2012-01-04|archive-date=2020-08-01|archive-url=https://web.archive.org/web/20200801194117/https://www.cambridge.org/core/books/historical-eclipses-and-earths-rotation/5666AB5AE48DE13AB0D28CEEFC765C50|url-status=live}}</ref> For comparison, the longest total eclipse of the 20th century at 7&nbsp;min 8&nbsp;s occurred on [[Solar eclipse of June 20, 1955|June 20, 1955]], and there will be no total solar eclipses over 7&nbsp;min in duration in the 21st century.<ref>Mobberley, p. 10</ref>

It is possible to predict other eclipses using [[eclipse cycle]]s. The [[Saros cycle|saros]] is probably the best known and one of the most accurate. A saros lasts 6585.3 days (a little over 18 years), which means that, after this period, a practically identical eclipse will occur. The most notable difference will be a westward shift of about 120° in longitude (due to the 0.3 days) and a little in latitude (north-south for odd-numbered cycles, the reverse for even-numbered ones). A saros series always starts with a partial eclipse near one of Earth's polar regions, then shifts over the globe through a series of annular or total eclipses, and ends with a partial eclipse at the opposite polar region. A saros series lasts 1226 to 1550 years and 69 to 87 eclipses, with about 40 to 60 of them being central.<ref>{{cite web|first=Fred |last=Espenak |title=Eclipses and the Saros |url=http://sunearth.gsfc.nasa.gov/eclipse/SEsaros/SEsaros.html |publisher=NASA Goddard Space Flight Center|website=NASA Eclipse web site|date=August 28, 2009 |access-date=January 15, 2012 |url-status=dead |archive-url=https://archive.today/20120524183445/http://sunearth.gsfc.nasa.gov/eclipse/SEsaros/SEsaros.html |archive-date=May 24, 2012}}</ref>

===Frequency per year===
Between two and five solar eclipses occur every year, with at least one per [[eclipse season]]. Since the [[Gregorian calendar]] was instituted in 1582, years that have had five solar eclipses were 1693, 1758, 1805, 1823, 1870, and 1935. The next occurrence will be 2206.<ref>{{cite magazine|date=1935|title=Calendar years with five solar eclipses|bibcode=1935PA.....43..412P |last=Pogo |first=Alexander |volume=43 |page=412 |magazine=Popular Astronomy}}</ref> On average, there are about 240 solar eclipses each century.<ref>{{Cite web|url = http://www.timeanddate.com/eclipse/solar-eclipse-frequency.html|title = What are solar eclipses and how often do they occur?|access-date = 2014-11-23|website = timeanddate.com|archive-date = 2017-02-02|archive-url = https://web.archive.org/web/20170202025545/https://www.timeanddate.com/eclipse/solar-eclipse-frequency.html|url-status = live}}</ref>

{| class=wikitable
|+ The five solar eclipses of 1935
|-
![[Solar eclipse of January 5, 1935|January 5]]
![[Solar eclipse of February 3, 1935|February 3]]
![[Solar eclipse of June 30, 1935|June 30]]
![[Solar eclipse of July 30, 1935|July 30]]
![[Solar eclipse of December 25, 1935|December 25]]
|-
!Partial<br />(south)
!Partial<br />(north)
!Partial<br />(north)
!Partial<br />(south)
!Annular<br />(south)
|- align=center
|[[File:SE1935Jan05P.png|150px]]<br />Saros 111
|[[File:SE1935Feb03P.png|150px]]<br />Saros 149
|[[File:SE1935Jun30P.png|150px]]<br />Saros 116
|[[File:SE1935Jul30P.png|150px]]<br />Saros 154
|[[File:SE1935Dec25A.png|150px]]<br />Saros 121
|}

===Final totality===
Total solar eclipses are seen on Earth because of a fortuitous combination of circumstances. Even on Earth, the diversity of eclipses familiar to people today is a temporary (on a geological time scale) phenomenon. Hundreds of millions of years in the past, the Moon was closer to Earth and therefore apparently larger, so every solar eclipse was total or partial, and there were no annular eclipses. Due to [[tidal acceleration]], the orbit of the Moon around Earth becomes approximately 3.8&nbsp;cm more distant each year. Millions of years in the future, the Moon will be too far away to fully occlude the Sun, and no total eclipses will occur. In the same timeframe, the Sun may become brighter, making it appear larger in size.<ref name="fourmilab">{{cite web|last=Walker|first=John|url=http://www.fourmilab.ch/images/peri_apo/|title=Moon near Perigee, Earth near Aphelion|website=Fourmilab|date=July 10, 2004|access-date=March 7, 2010|archive-date=December 8, 2013|archive-url=https://web.archive.org/web/20131208153430/http://www.fourmilab.ch/images/peri_apo/|url-status=live}}</ref> Estimates of the time when the Moon will be unable to occlude the entire Sun when viewed from Earth range between 650&nbsp;million<ref>{{cite news|last1=Mayo|first1=Lou|title=WHAT'S UP? The Very Last Solar Eclipse!|url=https://eclipse2017.nasa.gov/what%E2%80%99s-very-last-solar-eclipse|access-date=22 August 2017|work=[[NASA]]|url-status=dead|archive-url=https://web.archive.org/web/20170822023627/https://eclipse2017.nasa.gov/what%E2%80%99s-very-last-solar-eclipse|archive-date=2017-08-22}}</ref> and 1.4&nbsp;billion years in the future.<ref name="fourmilab"/>

==Viewing==
[[File:2017 Total Solar Eclipse with Audience Reaction.webm|thumb|[[Solar eclipse of August 21, 2017|2017 total solar eclipse]] viewed in real time with audience reactions]]
Looking directly at the [[photosphere]] of the Sun (the bright disk of the Sun itself), even for just a few seconds, can cause permanent [[Solar retinopathy|damage]] to the [[retina]] of the eye, because of the intense visible and invisible radiation that the photosphere emits. This damage can result in impairment of vision, up to and including [[blindness]]. The retina has no sensitivity to pain, and the effects of retinal damage may not appear for hours, so there is no warning that injury is occurring.<ref>{{cite web|first=Fred|last=Espenak|title=Eye Safety During Solar Eclipses|url=http://sunearth.gsfc.nasa.gov/eclipse/SEhelp/safety.html|date=July 11, 2005|publisher=NASA Goddard Space Flight Center|website=NASA Eclipse web site|access-date=January 15, 2012|url-status=dead|archive-url=https://archive.today/20120716084105/http://sunearth.gsfc.nasa.gov/eclipse/SEhelp/safety.html|archive-date=July 16, 2012}}</ref><ref>{{Cite journal|title=UK hospitals assess eye damage after solar eclipse|journal=British Medical Journal|date=August 21, 1999|author=Dobson, Roger|volume=319|issue=7208|page=469|doi=10.1136/bmj.319.7208.469|pmid=10454393|pmc=1116382}}</ref>

Under normal conditions, the Sun is so bright that it is difficult to stare at it directly. However, during an eclipse, with so much of the Sun covered, it is easier and more tempting to stare at it. Looking at the Sun during an eclipse is as dangerous as looking at it outside an eclipse, except during the brief period of totality, when the Sun's disk is completely covered (totality occurs only during a total eclipse and only very briefly; it does not occur during a partial or annular eclipse). Viewing the Sun's disk through any kind of optical aid (binoculars, a telescope, or even an optical camera viewfinder) is extremely hazardous and can cause irreversible eye damage within a fraction of a second.<ref>{{cite news|first=Alan M.|last=MacRobert|title=How to Watch a Partial Solar Eclipse Safely|work=Sky & Telescope|date=8 August 2006|url=https://skyandtelescope.org/observing/celestial-objects-to-watch/eclipses/how-to-watch-a-partial-solar-eclipse-safely/|access-date=August 4, 2007}}</ref><ref>{{cite web|first=B. Ralph|last=Chou|title=Eye safety during solar eclipses|publisher=NASA Goddard Space Flight Center|website=NASA Eclipse web site|url=http://eclipse.gsfc.nasa.gov/SEhelp/safety2.html|date=July 11, 2005|access-date=January 15, 2012|archive-date=November 14, 2020|archive-url=https://web.archive.org/web/20201114001510/https://eclipse.gsfc.nasa.gov/SEhelp/safety2.html|url-status=live}}</ref>

===Partial and annular eclipses===
{{multiple image
| align     = right
| direction = horizontal
| image1    = Eclipsbrilletje.JPG
| width1    = 180
| caption1  = [[Solar viewer|Eclipse glasses]] filter out eye damaging radiation, allowing direct viewing of the Sun during all partial eclipse phases; they are not used during totality, when the Sun is completely eclipsed
| image2    = Solar eclipse in Turkey March 2006.jpg
| width2    = 220
| caption2  = Pinhole projection method of observing partial solar eclipse. Insert (upper left): partially eclipsed Sun photographed with a white solar filter. Main image: projections of the partially eclipsed Sun (bottom right)
}}
Viewing the Sun during partial and annular eclipses (and during total eclipses outside the brief period of totality) requires special eye protection, or indirect viewing methods if eye damage is to be avoided. The Sun's disk can be viewed using appropriate filtration to block the harmful part of the Sun's radiation. Sunglasses do not make viewing the Sun safe. Only properly designed and certified solar filters should be used for direct viewing of the Sun's disk.<ref>{{cite web|author1=Littmann, Mark|author2=Willcox, Ken|author3=Espenak, Fred|date=1999|title=Observing Solar Eclipses Safely|url=http://www.mreclipse.com/Totality3/TotalityCh11.html|website=MrEclipse.com|access-date=January 15, 2012|archive-date=July 26, 2020|archive-url=https://web.archive.org/web/20200726061703/http://www.mreclipse.com/Totality3/TotalityCh11.html|url-status=live}}</ref> Especially, self-made filters using common objects such as a [[floppy disk]] removed from its case, a [[Compact Disc]], a black colour slide film, smoked glass, etc. must be avoided.<ref>{{cite web|url=http://www.mreclipse.com/Special/filters.html|author=Chou, B. Ralph|date=January 20, 2008|title=Eclipse Filters|website=MrEclipse.com|access-date=January 4, 2012|archive-date=November 27, 2020|archive-url=https://web.archive.org/web/20201127012430/http://mreclipse.com/Special/filters.html|url-status=live}}</ref><ref name="perkins"/>

The safest way to view the Sun's disk is by indirect projection.<ref name="Harrington25">Harrington, p. 25</ref> This can be done by projecting an image of the disk onto a white piece of paper or card using a pair of binoculars (with one of the lenses covered), a telescope, or another piece of cardboard with a small hole in it (about 1&nbsp;mm diameter), often called a [[pinhole camera]]. The projected image of the Sun can then be safely viewed; this technique can be used to observe [[sunspot]]s, as well as eclipses. Care must be taken, however, to ensure that no one looks through the projector (telescope, pinhole, etc.) directly.<ref>Harrington, p. 26</ref> A kitchen [[colander]] with small holes can also be used to project multiple images of the partially eclipsed Sun onto the ground or a viewing screen. Viewing the Sun's disk on a video display screen (provided by a [[video camera]] or [[digital camera]]) is safe, although the camera itself may be damaged by direct exposure to the Sun. The optical viewfinders provided with some video and digital cameras are not safe. Securely mounting #14 welder's glass in front of the lens and viewfinder protects the equipment and makes viewing possible.<ref name="perkins">{{cite web|url=http://perkins.owu.edu/solar_viewing_safety.htm|title=Solar Viewing Safety|website=[[Perkins Observatory]]|access-date=January 15, 2012|archive-date=July 14, 2020|archive-url=https://web.archive.org/web/20200714011852/http://perkins.owu.edu/solar_viewing_safety.htm|url-status=live}}</ref> Professional workmanship is essential because of the dire consequences any gaps or detaching mountings will have. In the partial eclipse path, one will not be able to see the corona or nearly complete darkening of the sky. However, depending on how much of the Sun's disk is obscured, some darkening may be noticeable. If three-quarters or more of the Sun is obscured, then an effect can be observed by which the daylight appears to be dim, as if the sky were overcast, yet objects still cast sharp shadows.<ref>Harrington, p. 40</ref>

===Totality===
{{multiple image
| header    = [[Solar eclipse of August 21, 2017]]
| align     = right
| direction = horizontal
| image1    = August 21 2017 solar eclipse baily beads TLR2.jpg
| width1    = 160
| caption1  = [[Baily's beads]], sunlight visible through lunar valleys
| image2    = A644, August 21, 2017 total solar eclipse composite image with corona, prominences and diamond ring.jpg
| width2    = 184
| caption2  = Composite image with [[solar corona|corona]], [[solar prominence|prominences]], and diamond ring effect
}}
When the shrinking visible part of the photosphere becomes very small, [[Baily's beads]] will occur. These are caused by the sunlight still being able to reach Earth through lunar valleys. Totality then begins with the [[diamond ring effect]], the last bright flash of sunlight.<ref name="total">{{cite web|author1=Littmann, Mark|author2=Willcox, Ken|author3=Espenak, Fred|date=1999|title=The Experience of Totality|url=http://www.mreclipse.com/Totality/TotalityCh01.html|website=MrEclipse.com|access-date=January 15, 2012|archive-url=https://web.archive.org/web/20120204074827/http://www.mreclipse.com/Totality/TotalityCh01.html|archive-date=February 4, 2012}}</ref>

It is safe to observe the total phase of a solar eclipse directly only when the Sun's photosphere is completely covered by the Moon, and not before or after totality.<ref name="Harrington25"/> During this period, the Sun is too dim to be seen through filters. The Sun's faint [[solar corona|corona]] will be visible, and the [[chromosphere]], [[solar prominence]]s, [[coronal streamer]]s and possibly even a [[solar flare]] may be seen. At the end of totality, the same effects will occur in reverse order, and on the opposite side of the Moon.<ref name="total"/>

===Eclipse chasing===
{{main|Eclipse chasing}}
A dedicated group of eclipse chasers have pursued the observation of solar eclipses when they occur around Earth.<ref>{{cite book|author=Kate Russo|title=Total Addiction: The Life of an Eclipse Chaser|url=https://books.google.com/books?id=AoVP-NdzkFsC|date=2012|publisher=Springer Science & Business Media|isbn=978-3-642-30481-1|access-date=24 August 2017|archive-date=9 December 2019|archive-url=https://web.archive.org/web/20191209174125/https://books.google.com/books?id=AoVP-NdzkFsC|url-status=live}}</ref> A person who chases eclipses is known as an umbraphile, meaning shadow lover.<ref name="sola_Umbr">{{Cite web| title = Umbraphile, Umbraphilia, Umbraphiles, and Umbraphiliacs – Solar Eclipse with the Sol Alliance| author = Kelly, Pat| work = Solar Eclipse with the Sol Alliance| date = 2017-07-06| access-date = 2017-08-24| url = http://solareclipselive.org/umbraphile-umbrapilia-umbraphiles-umbraphiliacs/| archive-date = 2019-08-13| archive-url = https://web.archive.org/web/20190813044012/https://solareclipselive.org/umbraphile-umbrapilia-umbraphiles-umbraphiliacs/| url-status = live}}</ref> Umbraphiles travel for eclipses and use various tools to help view the sun including [[solar viewer|solar viewing glasses]], also known as eclipse glasses, as well as telescopes.<ref name="ecli_Safe">{{Cite web| title = How to View the 2017 Solar Eclipse Safely| work = eclipse2017.nasa.gov| access-date = 2017-08-24| url = https://eclipse2017.nasa.gov/safety| archive-url = https://web.archive.org/web/20170824010442/https://eclipse2017.nasa.gov/safety| archive-date = 2017-08-24}}</ref><ref name="atla_Chas">{{Cite web| title = Chasing Totality: A Look Into the World of Umbraphiles| author = Wright, Andy| work = Atlas Obscura| date = 2017-08-16| access-date = 2017-08-24| url = http://www.atlasobscura.com/articles/total-eclipse-of-the-heart| archive-date = 2020-12-14| archive-url = https://web.archive.org/web/20201214163218/https://www.atlasobscura.com/articles/total-eclipse-of-the-heart| url-status = live}}</ref>

===Photography===
[[File:2008-08-01 Solar eclipse progression with timestamps.jpg|thumb|270px|The progression of a [[Solar eclipse of August 1, 2008|solar eclipse on August 1, 2008]] in [[Novosibirsk]], [[Russia]]. All times UTC (local time was UTC+7). The time span between shots is three minutes.]]
The first known photograph of a solar eclipse was taken on July 28, 1851, by [[Julius Berkowski|Johann Julius Friedrich Berkowski]], using the [[daguerreotype]] process.<ref>{{Cite web |last=Weitering |first=Hanneke |date=2017-07-28 |title=1st Photo of a Total Solar Eclipse Was Taken 166 Years Ago Today |url=https://www.space.com/37656-first-total-solar-eclipse-photo-ever.html |access-date=2024-04-08 |website=Space.com |language=en}}</ref><ref>{{Cite magazine |last=Farber |first=Madeline |date=2017-08-11 |title=This Is the First-Ever Photo of a Total Solar Eclipse |url=https://time.com/4883424/solar-eclipse-first-photo-taken/ |access-date=2024-04-09 |magazine=TIME |language=en}}</ref>

Photographing an eclipse is possible with fairly common camera equipment. In order for the disk of the Sun/Moon to be easily visible, a fairly high magnification [[long focus lens]] is needed (at least 200&nbsp;mm for a 35&nbsp;mm camera), and for the disk to fill most of the frame, a longer lens is needed (over 500&nbsp;mm). As with viewing the Sun directly, looking at it through the optical viewfinder of a camera can produce damage to the retina, so care is recommended.<ref>{{cite web|author=Kramer, Bill|url=http://www.eclipse-chasers.com/eclphot.htm |title=Photographing a Total Solar Eclipse|website=Eclipse-chasers.com|access-date=March 7, 2010|archive-url=https://web.archive.org/web/20090129100143/http://eclipse-chasers.com/eclphot.htm|archive-date=January 29, 2009}}</ref> Solar filters are required for digital photography even if an optical viewfinder is not used. Using a camera's live view feature or an electronic viewfinder is safe for the human eye, but the Sun's rays could potentially irreparably damage digital image sensors unless the lens is covered by a properly designed solar filter.<ref>{{cite web |url=https://www.bhphotovideo.com/explora/photography/tips-and-solutions/how-photograph-solar-eclipse |title=How to Photograph a Solar Eclipse |first=Todd |last=Vorenkamp |website=[[B&H Photo Video]] |date=April 2017 |access-date=August 19, 2017 |archive-date=July 1, 2019 |archive-url=https://web.archive.org/web/20190701075440/https://www.bhphotovideo.com/explora/photography/tips-and-solutions/how-photograph-solar-eclipse |url-status=live }}</ref>

{{Multiple image
| image1            = Eclipse shadows.svg
| caption1          = Pinholes in shadows during no eclipse (1 & 4), a partial eclipse (2 & 5) and an annular eclipse (3 & 6)
| image2            = 2024 Eclipse Shadows.jpg
| caption2          = Pinhole shadows during the Solar eclipse of April 8, 2024, as seen from Winder, Georgia.
}}

==Historical eclipses==
{{further|Eclipses in mythology and culture|Lists of solar eclipses}}
[[File:Antoinecaronq571Getty.jpg|thumb|upright=0.9|''Astronomers Studying an Eclipse'', [[Antoine Caron]], 1571]]
Historical eclipses are a very valuable resource for historians, in that they allow a few historical events to be dated precisely, from which other dates and ancient calendars may be deduced.<ref>{{Cite book|url=http://atena.beic.it/webclient/DeliveryManager?pid=13450778&search_terms=DTL54|title=Acta Eruditorum|year=1762|location=Leipzig|publication-date=1762|pages=168|access-date=2018-06-06|archive-date=2020-07-31|archive-url=https://web.archive.org/web/20200731015814/http://atena.beic.it/view/action/error.do|url-status=live}}</ref> The oldest recorded solar eclipse was recorded on a clay tablet found at [[Ugarit]], in modern [[Syria]], with two plausible dates usually cited: 3 May 1375 BC or 5 March 1223 BC, the latter being favored by most recent authors on the topic.<ref>{{Cite web |title=Solar Physics Historical Timeline (1223 BC – 200 BC) {{!}} High Altitude Observatory |url=https://www2.hao.ucar.edu/education/solar-physics-timeline/1223bc-200bc#:~:text=1223%20BC:%20The%20oldest%20eclipse,recents%20authors%20on%20the%20topic. |access-date=2023-12-14 |website=www2.hao.ucar.edu}}</ref><ref>{{Cite web |last=Smith |first=Kiona N. |title=People Recorded A Total Solar Eclipse For The First Time 3,241 Years Ago |url=https://www.forbes.com/sites/kionasmith/2018/03/05/people-recorded-a-total-solar-eclipse-for-the-first-time-3241-years-ago/ |access-date=2023-12-14 |website=Forbes |language=en}}</ref> A [[Assyrian eclipse|solar eclipse of June 15, 763 BC]] mentioned in an [[Assyrian people|Assyrian]] text is important for the [[chronology of the ancient Near East]].<ref>{{cite web|url=http://www.staff.science.uu.nl/~gent0113/babylon/babybibl_chronology.htm|title=Astronomical Chronology|first=Robert Harry|last=van Gent|website=University of Utrecht|access-date=January 15, 2012|archive-date=July 28, 2020|archive-url=https://web.archive.org/web/20200728075453/https://webspace.science.uu.nl/~gent0113/babylon/babybibl_chronology.htm|url-status=live}}</ref> There have been other claims to date earlier eclipses. The legendary Chinese king [[Zhong Kang]] supposedly beheaded two astronomers, Hsi and Ho, who failed to predict an eclipse 4000 years ago.<ref>Harrington, p. 2</ref> Perhaps the earliest still-unproven claim is that of archaeologist Bruce Masse, who putatively links an eclipse that occurred on May 10, 2807, BC with a possible [[impact event|meteor impact]] in the [[Indian Ocean]] on the basis of several ancient [[flood myth]]s that mention a total solar eclipse.<ref>{{Cite news |last=Blakeslee |first=Sandra |title=Ancient Crash, Epic Wave |work=The New York Times |date=November 14, 2006 |url=https://www.nytimes.com/2006/11/14/science/14WAVE.html |access-date=November 14, 2006 |archive-date=April 11, 2009 |archive-url=https://web.archive.org/web/20090411103836/http://www.nytimes.com/2006/11/14/science/14WAVE.html |url-status=live }}</ref>

[[File:Ibn Yunus eclipses 1004 CE manuscript records Arabic.jpg|thumb|upright|left|Records of the solar eclipses of 993 and 1004 as well as the lunar eclipses of 1001 and 1002 by [[Ibn Yunus]] of Cairo (c. 1005).]]
Eclipses have been interpreted as [[omen]]s, or portents.<ref>Steel, p. 1</ref> The ancient Greek historian [[Herodotus]] wrote that [[Thales|Thales of Miletus]] predicted [[Eclipse of Thales|an eclipse that occurred during a battle]] between the [[Medes]] and the [[Lydia]]ns. Both sides put down their weapons and declared peace as a result of the eclipse.<ref>Steel, pp. 84–85</ref> The exact eclipse involved remains uncertain, although the issue has been studied by hundreds of ancient and modern authorities. One likely candidate took place on May 28, 585 BC, probably near the [[Halys River|Halys]] river in [[Asia Minor]].<ref>{{cite web|first=David|last=Le Conte|date=December 6, 1998|title=Eclipse Quotations|url=http://www.mreclipse.com/Special/quotes1.html|website=MrEclipse.com|access-date=January 8, 2011|archive-date=October 17, 2020|archive-url=https://web.archive.org/web/20201017144110/http://www.mreclipse.com/Special/quotes1.html|url-status=live}}</ref> An eclipse recorded by Herodotus before [[Xerxes I|Xerxes]] departed for his expedition against [[Ancient Greece|Greece]],<ref>{{Cite book |last=Herodotus |title=Book VII |url=http://www.bostonleadershipbuilders.com/herodotus/book07.htm |page=37 |access-date=2008-07-13 |archive-date=2008-08-19 |archive-url=https://web.archive.org/web/20080819152623/http://www.bostonleadershipbuilders.com/herodotus/book07.htm |url-status=live }}</ref> which is traditionally dated to 480 BC, was matched by [[John Russell Hind]] to an annular eclipse of the Sun at [[Sardis]] on February 17, 478 BC.<ref>{{Cite book|last=Chambers|first=G. F. |title=A Handbook of Descriptive and Practical Astronomy|publisher=Clarendon Press|location=Oxford|date=1889|page=323}}</ref> Alternatively, a partial eclipse was visible from Persia on October 2, 480 BC.<ref name="Espenak">{{cite web|first=Fred|last=Espenak|title=Solar Eclipses of Historical Interest|url=http://sunearth.gsfc.nasa.gov/eclipse/SEhistory/SEhistory.html|access-date=December 28, 2011|publisher=NASA Goddard Space Flight Center|website=NASA Eclipse web site|url-status=dead|archive-url=https://web.archive.org/web/20080309073832/http://sunearth.gsfc.nasa.gov/eclipse/SEhistory/SEhistory.html|archive-date=March 9, 2008}}</ref> Herodotus also reports a solar eclipse at [[Sparta]] during the [[Second Persian invasion of Greece]].<ref>{{Cite book |last=Herodotus |title=Book IX |url=http://www.bostonleadershipbuilders.com/herodotus/book09.htm |page=10 |access-date=2008-07-14 |archive-date=2020-07-26 |archive-url=https://web.archive.org/web/20200726055223/http://www.bostonleadershipbuilders.com/herodotus/book09.htm |url-status=live }}</ref> The date of the eclipse (August 1, 477 BC) does not match exactly the conventional dates for the invasion accepted by historians.<ref>{{Cite magazine|first=Bradley E.|last= Schaefer |title=Solar Eclipses That Changed the World |magazine=Sky & Telescope |date=May 1994|volume=87|issue=5|pages=36–39|bibcode = 1994S&T....87...36S }}</ref>

In ancient China, where solar eclipses were known as an "eating of the Sun" ({{transl|cmn|rìshí}} {{lang|zh|日食}}), the earliest records of eclipses date to around 720 BC.<ref name="SciAm">{{cite magazine|author=Stephenson, F. Richard|date=1982|title=Historical Eclipses|magazine=Scientific American|volume=247|issue=4|pages=154–163|bibcode = 1982SciAm.247d.154S }}</ref> The 4th century BC astronomer [[Shi Shen]] described the prediction of eclipses by using the relative positions of the Moon and Sun.<ref name=Needham411>{{Cite book|last=Needham|first=Joseph|date=1986|title=Science and Civilization in China: Volume 3|location=Taipei|publisher=Caves Books|oclc=48999277|pages=411–413}}</ref>

Attempts have been made to establish the exact date of [[Good Friday]] by assuming that the [[Crucifixion darkness and eclipse|darkness described at Jesus's crucifixion]] was a solar eclipse. This research has not yielded conclusive results,<ref>{{Cite journal|first1=C. J. |last1=Humphreys|first2=W. G. |last2=Waddington |title=Dating the Crucifixion |journal=Nature |volume=306 |issue=5945 |date=1983 |pages=743–746 |doi=10.1038/306743a0|bibcode = 1983Natur.306..743H |s2cid=4360560}}</ref><ref>{{Cite book |first=Mark |last=Kidger |date=1999 |title=The Star of Bethlehem: An Astronomer's View |location=Princeton, NJ |publisher=Princeton University Press |pages=[https://archive.org/details/starofbethlehema00kidg/page/68 68–72] |isbn=978-0-691-05823-8 |url=https://archive.org/details/starofbethlehema00kidg/page/68 }}</ref> and Good Friday is recorded as being at [[Passover]], which is held at the time of a full moon. Further, the darkness lasted from the sixth hour to the ninth, or three hours, which is much, much longer than the eight-minute upper limit for any solar eclipse's totality. Contemporary chronicles wrote about an eclipse at the beginning of May [[664]] that coincided with the beginning of the [[plague of 664]] in the British isles.<ref>{{cite web |url=https://www.rte.ie/brainstorm/2020/0513/1138201-ireland-664-ad-plague-history/ |title=Reeling in the years: why 664 AD was a terrible year in Ireland |work=rte.ie |first=Dáibhí |last=Ó Cróinín
|date=13 May 2020 |archive-url=https://web.archive.org/web/20210108205541/https://www.rte.ie/brainstorm/2020/0513/1138201-ireland-664-ad-plague-history/ |archive-date=2021-01-08 |access-date=January 9, 2021}}</ref> In the Western hemisphere, there are few reliable records of eclipses before AD 800, until the advent of Arab and monastic observations in the early medieval period.<ref name="SciAm"/> 

A [[Solar eclipse of January 27, 632|solar eclipse took place on January 27, 632 over Arabia]] during [[Muhammad]]'s lifetime. Muhammad denied the eclipse had anything to do with his son dying earlier that day, saying "The sun and the moon do not eclipse because of the death of someone from the people but they are two signs amongst the signs of God."<ref>{{cite web|title=Translation of Sahih Bukhari, Book 18|url=https://www.iium.edu.my/deed/hadith/bukhari/018_sbt.html#:~:text=The%20Prophet%20said%2C%20%22The%20sun}}</ref> The Cairo astronomer [[Ibn Yunus]] wrote that the calculation of eclipses was one of the many things that connect astronomy with the [[Islamic law]], because it allowed knowing when [[Salat al-Kusuf|a special prayer]] can be made.<ref>{{cite encyclopedia|title=General survey of Arabic astronomy|encyclopedia=Encyclopedia of the History of Arabic Science|volume=I|author=Regis Morelon|publisher=Routledge |page=15|date=1996|editor=Roshdi Rashed}}</ref> The first recorded observation of the corona was made in [[Constantinople]] in AD 968.<ref name="Espenak"/><ref name="SciAm"/>[[File:Course of moon shadow 2.=12. 8. 1654 figured in advance by Erhard Weigel.jpg|thumb|[[Erhard Weigel]], predicted course of Moon shadow on 12 August 1654 ([[Old Style and New Style dates|O.S.]] 2&nbsp;August)]]

The first known telescopic observation of a total solar eclipse was made in France in 1706.<ref name="SciAm" /> Nine years later, English astronomer [[Edmund Halley]] accurately predicted and observed the [[solar eclipse of May 3, 1715]].<ref name="Espenak" /><ref name="SciAm" /> By the mid-19th century, scientific understanding of the Sun was improving through observations of the Sun's corona during solar eclipses. The corona was identified as part of the Sun's atmosphere in [[Solar eclipse of July 8, 1842|1842]], and the first photograph (or [[daguerreotype]]) of a total eclipse was taken of the [[solar eclipse of July 28, 1851]].<ref name="Espenak" /> [[Spectroscope]] observations were made of the [[solar eclipse of August 18, 1868]], which helped to determine the chemical composition of the Sun.<ref name="Espenak" />

[[John Fiske (philosopher)|John Fiske]] summed up myths about the solar eclipse like this in his 1872 book ''Myth and Myth-Makers'', {{Quotation| the myth of Hercules and Cacus, the fundamental idea is the victory of the solar god over the robber who steals the light. Now whether the robber carries off the light in the evening when Indra has gone to sleep, or boldly rears his black form against the sky during the daytime, causing darkness to spread over the earth, would make little difference to the framers of the myth. To a chicken a solar eclipse is the same thing as nightfall, and he goes to roost accordingly. Why, then, should the primitive thinker have made a distinction between the darkening of the sky caused by black clouds and that caused by the rotation of the earth? He had no more conception of the scientific explanation of these phenomena than the chicken has of the scientific explanation of an eclipse. For him it was enough to know that the solar radiance was stolen, in the one case as in the other, and to suspect that the same demon was to blame for both robberies.<ref>{{Cite book|url=http://www.gutenberg.org/ebooks/1061|title=Myths and Myth-Makers Old Tales and Superstitions Interpreted by Comparative Mythology|first=John|last=Fiske|date=1997|via=Project Gutenberg|access-date=February 12, 2017|archive-date=July 26, 2020|archive-url=https://web.archive.org/web/20200726050744/http://www.gutenberg.org/ebooks/1061|url-status=live}}</ref>}}

==Particular observations, phenomena and impact==
[[File:Screenshot from ESOcast 170 (42306775705).jpg|thumb|Simulated solar eclipse with a still illuminated and refracting horizon, as well as the [[coronal streamer]]s,]]
A total solar eclipse provides a rare opportunity to observe the [[solar corona|corona]] (the outer layer of the Sun's atmosphere). Normally this is not visible because the [[photosphere]] is much brighter than the corona. According to the point reached in the [[solar cycle]], the corona may appear small and symmetric, or large and fuzzy. It is very hard to predict this in advance.<ref>{{cite web|title=The science of eclipses|date=September 28, 2004|website=ESA|url=http://www.esa.int/esaSC/SEMYK9R1VED_index_0.html|access-date=August 4, 2007|archive-date=August 1, 2012|archive-url=https://web.archive.org/web/20120801125220/http://www.esa.int/esaSC/SEMYK9R1VED_index_0.html|url-status=live}}</ref>

Phenomena associated with eclipses include [[shadow bands]] (also known as ''flying shadows''), which are similar to shadows on the bottom of a swimming pool. They occur only just prior to and after totality, when a narrow solar crescent acts as an [[anisotropy|anisotropic]] light source.<ref>{{cite web|first=Dainis|last=Dravins|title=Flying Shadows|website=Lund Observatory|url=http://www.astro.lu.se/~dainis/HTML/FLYSHAD.html|access-date=January 15, 2012|archive-date=July 26, 2020|archive-url=https://web.archive.org/web/20200726045300/http://www.astro.lu.se/~dainis/HTML/FLYSHAD.html|url-status=live}}</ref> As the light filters through leaves of trees during a partial eclipse, the overlapping leaves create natural pinholes, displaying mini eclipses on the ground.<ref>{{cite web|url=https://www.nasa.gov/feature/goddard/2017/five-tips-from-nasa-for-photographing-the-total-solar-eclipse-on-aug-21|title=Five Tips from NASA for Photographing the Total Solar Eclipse on Aug. 21|last1=Johnson-Groh|first1=Mara|date=10 August 2017|website=NASA|access-date=21 September 2017|archive-date=18 August 2020|archive-url=https://web.archive.org/web/20200818062035/https://www.nasa.gov/feature/goddard/2017/five-tips-from-nasa-for-photographing-the-total-solar-eclipse-on-aug-21/|url-status=live}}</ref>

===1919 observations===
{{See also|Tests of general relativity#Deflection of light by the Sun}}
[[File:1919 eclipse positive.jpg|thumb|upright|Eddington's original photograph of the 1919 eclipse, which provided evidence for [[Albert Einstein|Einstein]]'s theory of [[general relativity]].]]

The observation of a total [[solar eclipse of May 29, 1919]], helped to confirm [[Albert Einstein|Einstein]]'s theory of [[general relativity]]. By comparing the apparent distance between stars in the constellation [[Taurus (constellation)|Taurus]], with and without the Sun between them, [[Arthur Eddington]] stated that the [[predictive power|theoretical predictions]] about [[gravitational lens]]es were confirmed.<ref name="Eddington1920">{{cite journal|last=Dyson|author2=Eddington, A.S.|author3=Davidson, C.R.|date=1920|title=A Determination of the Deflection of Light by the Sun's Gravitational Field, from Observations Made at the Solar eclipse of May 29, 1919|journal=[[Philosophical Transactions of the Royal Society A|Phil. Trans. Roy. Soc. A]]|volume=220|issue=571–81|pages=291–333|bibcode=1920RSPTA.220..291D|doi=10.1098/rsta.1920.0009|first=F.W.|url=https://zenodo.org/record/1432106|doi-access=free|access-date=August 27, 2019|archive-date=November 3, 2020|archive-url=https://web.archive.org/web/20201103181710/https://zenodo.org/record/1432106|url-status=live}}</ref> The observation with the Sun between the stars was possible only during totality since the stars are then visible. Though Eddington's observations were near the experimental limits of accuracy at the time, work in the later half of the 20th century confirmed his results.<ref>{{cite web|website=ESA|title=Relativity and the 1919 eclipse|date=September 13, 2004|url=http://www.esa.int/esaSC/SEM7I9R1VED_index_0.html|access-date=January 11, 2011|archive-date=October 21, 2012|archive-url=https://web.archive.org/web/20121021081121/http://www.esa.int/esaSC/SEM7I9R1VED_index_0.html|url-status=live}}</ref><ref>Steel, pp. 114–120</ref>

===Gravity anomalies===
There is a long history of observations of gravity-related phenomena during solar eclipses, especially during the period of totality. [[Maurice Allais]] reported observing unusual and unexplained movements during solar eclipses in both 1954 and 1959.<ref>{{Cite journal|first=Maurice |last=Allais |title=Should the Laws of Gravitation be Reconsidered? |journal=Aero/Space Engineering |volume=9 |pages=46–55 |date=1959}}</ref> The reality of this phenomenon, named the [[Allais effect]], has remained controversial. Similarly, in 1970, [[Erwin Saxl|Saxl]] and [[Mildred Allen (physicist)|Allen]] observed the sudden change in motion of a torsion pendulum; this phenomenon is called the Saxl effect.<ref>{{Cite journal|first1=Erwin J. |last1=Saxl|first2=Mildred |last2=Allen |title=1970 solar eclipse as 'seen' by a torsion pendulum |journal=[[Physical Review D]] |volume=3 |issue=4 |pages=823–825 |date=1971 |doi=10.1103/PhysRevD.3.823|bibcode = 1971PhRvD...3..823S }}</ref>

Observation during the 1997 solar eclipse by Wang ''et al.'' suggested a possible [[gravitational shielding]] effect,<ref>{{Cite journal|first=Qian-shen|last= Wang|author2=Yang, Xin-she |author3=Wu, Chuan-zhen |author4=Guo, Hong-gang |author5=Liu, Hong-chen |author6= Hua, Chang-chai |title=Precise measurement of gravity variations during a total solar eclipse |journal=Physical Review D |volume=62 |issue=4 |page=041101(R) |date=2000 |doi=10.1103/PhysRevD.62.041101 |bibcode = 2000PhRvD..62d1101W |arxiv = 1003.4947 |s2cid= 6846335}}</ref> which generated debate. In 2002, Wang and a collaborator published detailed data analysis, which suggested that the phenomenon still remains unexplained.<ref>{{Cite journal|first1=X. S. |last1=Yang |first2=Q. S. |last2=Wang |title=Gravity anomaly during the Mohe total solar eclipse and new constraint on gravitational shielding parameter |journal=Astrophysics and Space Science |volume=282 |issue=1 |pages=245–253 |date=2002 |doi=10.1023/A:1021119023985|bibcode = 2002Ap&SS.282..245Y |s2cid=118497439 }}</ref>

===Eclipses and transits===
In principle, the simultaneous occurrence of a solar eclipse and a [[Astronomical transit|transit]] of a planet is possible. But these events are extremely rare because of their short durations. The next anticipated simultaneous occurrence of a solar eclipse and a [[transit of Mercury]] will be on July 5, 6757, and a solar eclipse and a [[transit of Venus]] is expected on April 5, {{gaps|15|232}}.<ref>{{cite journal|author1=Meeus, J. |author2=Vitagliano, A. |date=2004|title=Simultaneous transits|journal=J. Br. Astron. Assoc.|volume=114|issue=3|pages=132–135|url=http://www.marco-peuschel.de/simtrans.pdf|archive-url=https://web.archive.org/web/20070710041555/http://www.marco-peuschel.de/simtrans.pdf|archive-date=July 10, 2007|bibcode = 2004JBAA..114..132M }}</ref>

More common, but still infrequent, is a [[astronomical conjunction|conjunction]] of a planet (especially, but not only, Mercury or Venus) at the time of a total solar eclipse, in which event the planet will be visible very near the eclipsed Sun, when without the eclipse it would have been lost in the Sun's glare. At one time, some scientists hypothesized that there may be a planet (often given the name [[Vulcan (hypothetical planet)|Vulcan]]) even closer to the Sun than Mercury; the only way to confirm its existence would have been to observe it in transit or during a total solar eclipse. No such planet was ever found, and [[general relativity]] has since explained the observations that led astronomers to suggest that Vulcan might exist.<ref>{{cite book|author=Grego, Peter|date=2008|title=Venus and Mercury, and How to Observe Them|publisher=Springer|isbn=978-0387742854 |page=3}}</ref>

===Artificial satellites===
[[File:Eclipse fromISS 2006-03-29.jpg|thumb|The Moon's shadow over [[Turkey]] and [[Cyprus]], seen from the [[International Space Station|ISS]] during a [[Solar eclipse of March 29, 2006|2006 total solar eclipse]].]]
[[File:ISS Transit composite during Solar Eclipse 8-21-17 near Banner, Wyoming.jpg|thumb|A composite image showing the ISS transit of the Sun while the 2017 solar eclipse was in progress]]

Artificial satellites can also pass in front of the Sun as seen from Earth, but none is large enough to cause an eclipse. At the altitude of the [[International Space Station]], for example, an object would need to be about {{convert|3.35|km|mi|2|abbr=on}} across to blot the Sun out entirely. These transits are difficult to watch because the zone of visibility is very small. The satellite passes over the face of the Sun in about a second, typically. As with a transit of a planet, it will not get dark.<ref>{{cite web |title=ISS-Venustransit |language=de |url=http://eclipse.astronomie.info/transit/venus/isstransit/isstransit.html |website=astronomie.info |access-date=2004-07-29 |archive-date=2020-07-28 |archive-url=https://web.archive.org/web/20200728093541/https://eclipse.astronomie.info/transit/venus/isstransit/isstransit.html |url-status=live }}</ref>

Observations of eclipses from spacecraft or artificial satellites orbiting above Earth's atmosphere are not subject to weather conditions. The crew of [[Gemini 12]] observed a total solar eclipse from space in 1966.<ref>{{cite web|title=JSC Digital Image Collection|url=http://images.jsc.nasa.gov/luceneweb/caption_direct.jsp?photoId=S66-63415|website=NASA Johnson Space Center|date=January 11, 2006|access-date=January 15, 2012|url-status=dead|archive-url=https://web.archive.org/web/20120204064644/http://images.jsc.nasa.gov/luceneweb/caption_direct.jsp?photoId=S66-63415|archive-date=February 4, 2012}}</ref> The partial phase of the [[Solar eclipse of August 11, 1999|1999 total eclipse]] was visible from [[Mir]].<ref>{{Cite APOD|title=Looking Back on an Eclipsed Earth |date=August 30, 1999|access-date=January 15, 2012}}</ref>

===Impact===
The [[solar eclipse of March 20, 2015]], was the first occurrence of an eclipse estimated to potentially have a significant impact on the power system, with the electricity sector taking measures to mitigate any impact. The [[synchronous grid of Continental Europe|continental Europe]] and [[National Grid (Great Britain)|Great Britain]] synchronous areas were estimated to have about 90 [[gigawatt]]s of [[solar power]] and it was estimated that production would temporarily decrease by up to 34 GW compared to a clear sky day.<ref name=eclImp>"[https://www.entsoe.eu/Documents/Publications/SOC/150219_Solar_Eclipse_Impact_Analysis_Final.pdf Solar Eclipse 2015 – Impact Analysis] {{Webarchive|url=https://web.archive.org/web/20170221054328/https://www.entsoe.eu/Documents/Publications/SOC/150219_Solar_Eclipse_Impact_Analysis_Final.pdf |date=2017-02-21 }}" pp. 3, 6–7, 13. ''[[European Network of Transmission System Operators for Electricity]]'', 19 February 2015. Accessed: 4 March 2015.</ref><ref>{{cite web|url=http://ing.dk/sites/ing/files/solformoerkelse.jpg|title=Curve of potential power loss|website=ing.dk|access-date=2015-03-04|archive-date=2020-07-28|archive-url=https://web.archive.org/web/20200728045324/https://ing.dk/sites/ing/files/solformoerkelse.jpg|url-status=live}}</ref><!--formula for Solar Obscuration Factor on page 16-->

Eclipses may cause the temperature to decrease by {{cvt|3|C-change|0}}, with [[wind power]] potentially decreasing as winds are reduced by {{convert|0.7|m|ft|sp=us}} per second.<ref name="RSwind">{{cite journal | last1 = Gray | first1 = S. L. | last2 = Harrison | first2 = R. G. | year = 2012 | title = Diagnosing eclipse-induced wind changes | url = http://rspa.royalsocietypublishing.org/content/468/2143/1839 | journal = [[Proceedings of the Royal Society]] | volume = 468 | issue = 2143 | pages = 1839–1850 | doi = 10.1098/rspa.2012.0007 | bibcode = 2012RSPSA.468.1839G | doi-access = free | access-date = 2015-03-04 | archive-date = 2015-03-04 | archive-url = https://web.archive.org/web/20150304105008/http://rspa.royalsocietypublishing.org/content/468/2143/1839 | url-status = live }}</ref>

In addition to the drop in light level and air temperature, animals change their behavior during totality. For example, birds and squirrels return to their nests and crickets chirp.<ref>{{cite web|url=https://eclipse2017.nasa.gov/how-eclipses-work|title=How Eclipses Work|last=Young|first=Alex|website=NASA|access-date=21 September 2017|archive-url=https://web.archive.org/web/20170918132039/https://eclipse2017.nasa.gov/how-eclipses-work|archive-date=2017-09-18}}</ref>

==Recent and forthcoming solar eclipses==
{{Main|List of solar eclipses in the 21st century}}
{{Further|Lists of solar eclipses}}{{More citations needed section|date=May 2024}}[[File:Solar eclipses 2021-2040.png|thumb|350px|Eclipse path for total and hybrid eclipses from 2021 to 2040]]
Eclipses occur only in the [[eclipse season]], when the Sun is close to either the ascending or descending [[Lunar node|node of the Moon]]. Each eclipse is separated by one, five or six [[lunation]]s ([[synodic month]]s), and the midpoint of each season is separated by 173.3 days, which is the mean time for the Sun to travel from one node to the next. The period is a little less than half a calendar year because the lunar nodes slowly regress. Because 223 synodic months is roughly equal to 239 [[anomalistic month]]s and 242 [[draconic month]]s, eclipses with similar geometry recur 223 synodic months (about 6,585.3 days) apart. This period (18 years 11.3 days) is a [[Saros (astronomy)|saros]]. Because 223 synodic months is not identical to 239 anomalistic months or 242 draconic months, saros cycles do not endlessly repeat. Each cycle begins with the Moon's shadow crossing Earth near the north or south pole, and subsequent events progress toward the other pole until the Moon's shadow misses Earth and the series ends.<ref name="period"/> Saros cycles are numbered; currently, cycles 117 to 156 are active.{{cn|date=May 2022}} 

===1997–2000===
{{Solar eclipse set 1997–2000}}

===2000–2003===
{{Solar eclipse set 2000–2003}}

===2004–2007===
{{Solar eclipse set 2004–2007}}

===2008–2011===
{{Solar eclipse set 2008–2011}}

===2011–2014===
{{Solar eclipse set 2011–2014}}

===2015–2018===
{{Solar eclipse set 2015–2018}}

===2018–2021===
{{Solar eclipse set 2018–2021}}

===2022–2025===
{{Solar eclipse set 2022–2025}}

===2026–2029===
{{Solar eclipse set 2026–2029}}

==See also==
* [[Lists of solar eclipses]]
* [[List of films featuring eclipses]]
* [[Apollo–Soyuz]]: First joint U.S.–Soviet space flight. Mission included an arranged eclipse of the Sun by the Apollo module to allow instruments on the Soyuz to take photographs of the solar corona.
* [[Eclipse chasing]]: Travel to eclipse locations for study and enjoyment
* [[Occultation]]: Generic term for occlusion of an object by another object that passes between it and the observer, thus revealing (for example) the presence of an exoplanet orbiting a distant star by eclipsing it as seen from Earth
* [[Eclipses in history and culture]]: treatment of solar and lunar eclipses by historical and contemporary society and religion
* [[Solar eclipses in fiction]]
* [[Solar eclipses on the Moon]]: Eclipse of the Sun by planet Earth, as seen from the Moon
** [[Lunar eclipse]]: Solar eclipse of the Moon, as seen from Earth; the shadow cast on the Moon by that eclipse
* [[Transit of Venus]]: Passage of the planet Venus between the Sun and Earth, as seen from Earth. Technically a partial eclipse.
* [[Transit of Deimos from Mars]]: Passage of the Martian moon Deimos between the Sun and Mars, as seen from Mars
* [[Transit of Phobos from Mars]]: Passage of the Martian moon Phobos between the Sun and Mars, as seen from Mars

==Footnotes==
{{reflist|group=Note}}

==References==
{{Reflist}}

==Bibliography==
* {{cite book|first1=Hermann|last1=Mucke|author1-link=Hermann Mucke (astronomer)|first2=Jean|last2=Meeus|author2-link=Jean Meeus|date=1992|edition=2|title=Canon of Solar Eclipses −2003 to +2526|publisher=Astronomisches Büro|location=Vienna}}
* {{cite book|last=Harrington|first=Philip S.|date=1997|title=Eclipse! The What, Where, When, Why and How Guide to Watching Solar and Lunar Eclipses|publisher=John Wiley and Sons|location=New York|isbn=0-471-12795-7|url=https://archive.org/details/eclipsewhatwhere00harr}}
* {{cite book|last=Steel|first=Duncan|author-link=Duncan Steel|date=1999|title=Eclipse: The celestial phenomenon which has changed the course of history|publisher=Headline|location=London|isbn=0-7472-7385-5}}
* {{cite book|last=Mobberley|first=Martin|date=2007|title=Total Solar Eclipses and How to Observe Them|series=Astronomers' Observing Guides|location=New York|publisher=Springer|isbn=978-0-387-69827-4}}
* {{cite book|first=Fred|last=Espenak|date=2015|title=Thousand Year Canon of Solar Eclipses 1501 to 2500|publisher=Astropixels Publishing|location=Portal AZ|isbn=978-1-941983-02-7|author-link=Fred Espenak}}
* {{cite book|first=Fred|last=Espenak|date=2016|title=21st Century Canon of Solar Eclipses|publisher=Astropixels Publishing|location=Portal AZ|isbn=978-1-941983-12-6}}
* {{cite book |last1=Fotheringham |first1=John Knight |author-link1=John Knight Fotheringham |title=[[s:Historical eclipses|Historical eclipses]]: being the Halley lecture delivered 17 May 1921 |date=1921 |publisher=Clarendon Press |location=Oxford |language=en}}

==External links==
{{Commons category}}
{{Wikivoyage|Solar eclipses}}
{{Spoken Wikipedia|date=2006-05-03|Solar_eclipse_Part_1.ogg|Solar_eclipse_Part_2.ogg}}
* [https://solarsystem.nasa.gov/eclipses/home/ NASA Eclipse Web Site, with information on future eclipses and eye safety information]
* [http://eclipse.gsfc.nasa.gov/eclipse.html NASA Eclipse Web Site (older version)]
* [http://www.eclipsewise.com/eclipse.html Eclipsewise], Fred Espenak's new eclipse site
* [http://andrew-lowe.ca/eclipse_page.htm Andrew Lowe's Eclipse Page], with maps and circumstances for 5000 years of solar eclipses
* [https://www.fraknoi.com/wp-content/uploads/2022/12/ECLIPSE-ACTIVITIES-for-Educators.pdf A Guide to Eclipse Activities for Educators], Explaining eclipses in educational settings
* [http://moonblink.info/Eclipse/ Detailed eclipse explanations and predictions], Hermit Eclipse
* [http://www.zam.fme.vutbr.cz/~druck/Eclipse/ Eclipse Photography], Prof. Miroslav Druckmüller
* [https://web.archive.org/web/20160415224149/http://shadowandsubstance.com/2017/2017e.html Animated maps of August 21, 2017 solar eclipses], Larry Koehn
* [http://xjubier.free.fr/en/site_pages/solar_eclipses/5MCSE/xSE_Five_Millennium_Canon.html Five Millennium (−1999 to +3000) Canon of Solar Eclipses Database], Xavier M. Jubier
* [http://alienworlds.southwales.ac.uk/solarEclipse.html Animated explanation of the mechanics of a solar eclipse] {{Webarchive|url=https://web.archive.org/web/20130525061317/http://alienworlds.southwales.ac.uk/solarEclipse.html |date=2013-05-25 }}, University of South Wales
* [http://www.twanight.org/newTWAN/gallery.asp?Gallery=Eclipses&page=1 Eclipse Image Gallery] {{Webarchive|url=https://web.archive.org/web/20161015033303/http://www.twanight.org/newTWAN/gallery.asp?Gallery=Eclipses&page=1 |date=2016-10-15 }}, The World at Night
* [https://web.archive.org/web/20140422080638/http://www.photoparsi.com/5/556-ring-of-fire-eclipse Ring of Fire Eclipse: 2012], Photos
* {{Cite Collier's|wstitle=Sun, Eclipses of the |short=x}}
* {{YouTube|f0eFjqvvd14|Centered and aligned video recording of Total Solar Eclipse 20th March 2015}}
* [http://digitalcollections.ucsc.edu/cdm/search/collection/p265101coll10/searchterm/Solar%20eclipses/mode/exact Solar eclipse photographs taken from the Lick Observatory from the Lick Observatory Records Digital Archive, UC Santa Cruz Library’s Digital Collections] {{Webarchive|url=https://web.archive.org/web/20200605233244/http://digitalcollections.ucsc.edu/cdm/search/collection/p265101coll10/searchterm/Solar%20eclipses/mode/exact |date=2020-06-05 }}
* {{YouTube|sr8ASPwrs58|Video with Total Solar Eclipse March 09 2016 (from the beginning to the total phase)}}
* [https://www.youtube.com/watch?v=2i4PJWCNBaM Total Solar Eclipse Shadow on Earth March 09 2016] [[CIMSSSatelite]]
* [https://www.solar-eclipse.info/en/eclipse/ List of all solar eclipses]
* [https://video.nationalgeographic.com/video/101-videos/solar-eclipse-101/ National Geographic Solar Eclipse 101 video] {{Webarchive|url=https://web.archive.org/web/20180804110250/https://video.nationalgeographic.com/video/101-videos/solar-eclipse-101 |date=2018-08-04 }}
* {{sister-inline|project=v
|links=[[v:Skygazing/Solar eclipse lab on a sunny day|Wikiversity has a solar eclipse lab that students can do on any sunny day.]]
|short=yes}}

{{Solar eclipses}}
{{The Sun}}
{{The Moon}}
{{Star}}
{{Portal bar|Astronomy|Stars|Spaceflight|Outer space|Solar System}}

{{Authority control}}
{{Featured article}}
{{DEFAULTSORT:Solar Eclipse}}
[[Category:Eclipses]]
[[Category:Solar eclipses| ]]