
, a solar eclipse
occurs when the Moon
passes between the Sun
and the Earth, and the Moon fully or partially blocks the Sun as viewed from a location on Earth. This can happen only during a new moon
, when the Sun and the Moon are in conjunction as seen from Earth. At least two, and up to five, solar eclipses occur each year; no more than two can be total eclipses. Total solar eclipses are nevertheless rare at any particular location because totality exists only along a narrow path on the Earth's surface traced by the Moon's umbra
.
Some people, sometimes referred to as "eclipse chasers" or "umbraphiles", will travel to remote locations to observe or witness a predicted central solar eclipse (see Types below).
781 BC The first historic solar eclipse is recorded in China.
763 BC Assyrians record a solar eclipse that is later used to fix the chronology of Mesopotamian history.
585 BC A solar eclipse occurs, as predicted by Greek philosopher and scientist Thales, while Alyattes is battling Cyaxares in the Battle of the Eclipse, leading to a truce. This is one of the cardinal dates from which other dates can be calculated.
1831 Nat Turner sees a solar eclipse, which he believes is a sign from God. Eight days later he and 70 other slaves kill approximately 55 whites in Southampton County, Virginia.
1919 Einstein's theory of general relativity is tested (later confirmed) by Arthur Eddington's observation of a total solar eclipse in Principe and by Andrew Crommelin in Sobral, Ceará, Brazil.
1999 A total Solar eclipse (Solar eclipse of August 11, 1999)
, a solar eclipse
occurs when the Moon
passes between the Sun
and the Earth, and the Moon fully or partially blocks the Sun as viewed from a location on Earth. This can happen only during a new moon
, when the Sun and the Moon are in conjunction as seen from Earth. At least two, and up to five, solar eclipses occur each year; no more than two can be total eclipses. Total solar eclipses are nevertheless rare at any particular location because totality exists only along a narrow path on the Earth's surface traced by the Moon's umbra
.
Some people, sometimes referred to as "eclipse chasers" or "umbraphiles", will travel to remote locations to observe or witness a predicted central solar eclipse (see Types below). The solar eclipse of August 11, 1999, in Europe
helped to increase public awareness of the phenomenon, which apparently led to an unusually large number of journeys made specifically to witness the annular solar eclipse of October 3, 2005, and of March 29, 2006.
The last total solar eclipse was the solar eclipse of July 11, 2010
; the next will be the solar eclipse of November 13, 2012
. The recent solar eclipse of June 1, 2011
and the Solar eclipse of July 1, 2011
, were partial eclipses (see Types below); the next partial eclipse will occur on November 25, 2011
.
A total solar eclipse is a natural phenomenon
. Nevertheless, in ancient times, and in some cultures today, solar eclipses have been attributed to supernatural
causes or regarded as bad omen
s. A total solar eclipse can be frightening to people who are unaware of their astronomical
explanation, as the Sun seems to disappear during the day and the sky darkens in a matter of minutes.
Types
There are four types of solar eclipses:
- A total eclipse occurs when the dark silhouette of the Moon completely obscures the intensely bright light of the Sun, allowing the much fainter solar coronaCoronaA corona is a type of plasma "atmosphere" of the Sun or other celestial body, extending millions of kilometers into space, most easily seen during a total solar eclipse, but also observable in a coronagraph...
to be visible. During any one eclipse, totality occurs at best only in a narrow track on the surface of the Earth. - An annular eclipse occurs when the Sun and Moon are exactly in line, but the apparent size of the Moon is smaller than that of the Sun. Hence the Sun appears as a very bright ring, or annulusAnnulus (mathematics)In mathematics, an annulus is a ring-shaped geometric figure, or more generally, a term used to name a ring-shaped object. Or, it is the area between two concentric circles...
, surrounding the outline of the Moon. - A hybrid eclipse (also called annular/total eclipse) shifts between a total and annular eclipse. At some points on the surface of the Earth it appears as a total eclipse, whereas at others it appears as annular. Hybrid eclipses are comparatively rare.
- A partial eclipse occurs when the Sun and Moon are not exactly in line and the Moon only partially obscures the Sun. This phenomenon can usually be seen from a large part of the Earth outside of the track of an annular or total eclipse. However, some eclipses can only be seen as a partial eclipse, because the umbraUmbraThe umbra, penumbra and antumbra are the names given to three distinct parts of a shadow, created by any light source. For a point source only the umbra is cast.These names are most often used to refer to the shadows cast by celestial bodies....
passes above the Earth's polar regions and never intersects the Earth's surface.
The Sun's distance from the 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.
The Moon's orbit around the Earth is an ellipse
, as is the Earth's orbit around the Sun; the apparent sizes of the Sun and Moon therefore vary. 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 the Earth (i.e., near its perigee
) can be a total eclipse because the Moon will appear to be large enough to cover completely the Sun's bright disk, or photosphere
; a total eclipse has a magnitude greater than 1. Conversely, an eclipse that occurs when the Moon is near its farthest distance from the Earth (i.e., near its apogee) can only be 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. Slightly more solar eclipses are annular than total because, on average, the Moon lies too far from Earth to cover the Sun completely. A hybrid eclipse occurs when the magnitude of an eclipse changes during the event from smaller than one to larger than one—or vice versa—so the eclipse appears to be total at some locations on Earth and annular at other locations.
Because the Earth's orbit around the Sun is also elliptical, the Earth's distance from the Sun similarly varies throughout the year. This affects the apparent sizes of the Sun and Moon in the same way, but not so much as the Moon's varying distance from the Earth. When the Earth approaches its farthest distance from the Sun in July, a total eclipse is somewhat more likely, whereas conditions favour an annular eclipse when the Earth approaches its closest distance to the Sun in January.
Terminology for central eclipse
Central eclipse is often used as a generic term for a total, annular, or hybrid eclipse. This is, however, not completely correct: the definition of a central eclipse is an eclipse during which the central line of the umbra touches the 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. The next non-central solar eclipse will be on April 29, 2014. This will be an annular eclipse. The next non-central total solar eclipse will be on April 9, 2043.The phases observed during a total eclipse are called:
- First Contact—when the moon's limb first becomes visible on the solar disk. Some also name individual phases between First and Second Contact e.g. Pac-Man phase.
- Second Contact—starting with Baily's Beads {caused by light shining through valleys on the moon's surface} and the Diamond Ring. Almost the entire disk is covered.
- Totality—the limb of the moon obscuring the entire disk of the sun and only the corona visible
- Third Contact—when the first bright light becomes visible and the shadow is moving away from the observer. Again a Diamond Ring may be observed
Geometry
The diagram to the right shows the alignment of the Sun, Moon and Earth during a solar eclipse. The dark gray region below the Moon is the umbra, where the Sun is completely obscured by the Moon. The small area where the umbra touches the Earth's surface is where a total eclipse can be seen. The larger light gray area is the penumbra, in which only a partial and annular eclipses can be seen.
The Moon's orbit around the Earth is inclined at an angle of just over 5 degrees to the plane of the Earth's orbit around the Sun (the ecliptic
). Because of this, at the time of a new moon, the Moon will usually pass above or below the Sun. A solar eclipse can occur only when the new moon occurs close to one of the points (known as node
s) where the Moon's orbit crosses the ecliptic.
As noted above, the Moon's orbit is also elliptical
. The Moon's distance from the Earth can vary by about 6% from its average value. Therefore, the Moon's apparent size varies with its distance from the Earth, and it is this effect that leads to the difference between total and annular eclipses. The distance of the Earth from the Sun also varies during the year, but this is a smaller effect. On average, the Moon appears to be slightly smaller than the Sun, so the majority (about 60%) of central eclipses are annular. It is only when the Moon is closer to the Earth than average (near its perigee
) that a total eclipse occurs.
| Moon | | Sun | |||
---|---|---|---|---|
At perigee (nearest) | At apogee (farthest) |
At perihelion (nearest) | At aphelion (farthest) |
|
Mean radius, r | 1737.1 kilometres (1,079.4 mi) | 696000 kilometres (432,475.4 mi) | ||
Distance, d | 363104 km (225,622.9 mi) | 405696 km (252,088.4 mi) | 147098070 km (91,402,730.3 mi) | 152097700 km (94,509,364.1 mi) |
Angular diameter, 2 × arctan(r / d) |
32' 54" (0.5482°) |
29' 26" (0.4907°) |
32' 32" (0.5422°) |
31' 28" (0.5244°) |
Apparent size to scale |
||||
Rank in descending order |
1st | 4th | 2nd | 3rd |
The Moon orbits the Earth in approximately 27.3 days, relative to a fixed frame of reference. This is known as the sidereal month. However, during one sidereal month, the 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
.
The Moon crosses from south to north of the ecliptic at its ascending node, and vice versa at its descending node. 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 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 draconic month.
Finally, the Moon's perigee is moving forwards in its orbit, and makes a complete circuit in about 9 years. The time between one perigee and the next is known as the anomalistic month.
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 apart, 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. This means that in any given year, there will always be at least two solar eclipses, and there can be as many as five. However, some are visible only as partial eclipses, because the umbra passes above Earth's north or south pole, and others are central only in remote regions of the Arctic
or Antarctic
.
Eclipses can only occur 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. 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. Since the eclipse limit creates a window of opportunity of up to 36 degrees (24 degrees for central eclipses), it is possible for partial (or rarely a partial and a central) eclipses to occur in consecutive months.
Path
During a central eclipse, the Moon's umbra (or antumbra, in the case of an annular eclipse) moves rapidly from west to east across the Earth. The Earth is also rotating from west to east, but the umbra always moves faster than any given point on the Earth's surface, so it almost always appears to move in a roughly west-east direction across a map of the Earth (there are some rare exceptions to this which can occur during an eclipse of the midnight sunin Arctic or Antarctic regions, for example on June 10
and December 4
, 2021).
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 over 250 km wide and the duration of totality may be over 7 minutes. Outside of the central track, a partial eclipse can usually be seen over a much larger area of the Earth.
Occurrence and cycles
Total solar eclipses are rare events. Although they occur somewhere on Earth every 18 months on average, it has been estimated that they recur at any given place only once every 370 years, on average. The total eclipse only lasts for a few minutes at that location, as the Moon's umbra moves eastward at over 1700 km/h. Totality can never last more than 7 min 31 s, and is usually much shorter: during each millenniumthere are typically fewer than 10 total solar eclipses exceeding 7 minutes. The last time this happened was June 30, 1973
(7 min 3 sec). Observers aboard a Concorde
aircraft were able to stretch totality to about 74 minutes by flying along the path of the Moon's umbra. The next eclipse exceeding seven minutes in duration will not occur until June 25, 2150
. The longest total solar eclipse during the 8,000 year period from 3000 BC to 5000 AD will occur on July 16, 2186
, when totality will last 7 min 29 s. For comparison, the longest eclipse of the 20th century occurred on June 20, 1955
and lasted 7 min 8 sec.
If the date and time of any solar eclipse are known, it is possible to predict other eclipses using eclipse cycle
s. Two such cycles are the saros
and the inex
. The saros is probably the best known and one of the most accurate eclipse cycles. The inex cycle is itself a poor cycle, but it is very convenient in the classification of eclipse cycles. After a saros finishes, a new saros series begins one inex later, hence its name: in-ex. A saros lasts 6,585.3 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 shift of 120° in longitude (due to the 0.3 days) and a little in latitude. 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 at the opposite polar region. A saros series lasts 1226 to 1550 years and 69 to 87 eclipses, with about 40 to 60 central.
Frequency per year
Solar eclipses can occur 2 to 5 times per year, at least once 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.
January 5 Solar eclipse of January 5, 1935 A partial solar eclipse occurred on January 5, 1935. It was the last eclipse of solar saros 111 with the moon's penumbra touching the earth for just 10 minutes. - External links :* http://eclipse.gsfc.nasa.gov/SEplot/SEplot1901/SE1935Jan05P.GIF... |
February 3 Solar eclipse of February 3, 1935 A partial solar eclipse occurred on February 3, 1935.- External links :* http://eclipse.gsfc.nasa.gov/SEplot/SEplot1901/SE1935Feb03P.GIF... |
June 30 Solar eclipse of June 30, 1935 A partial solar eclipse occurred on June 30, 1935. - External links :* http://eclipse.gsfc.nasa.gov/SEplot/SEplot1901/SE1935Jun30P.GIF... |
July 30 Solar eclipse of July 30, 1935 A partial solar eclipse occurred on July 30, 1935.- External links :* http://eclipse.gsfc.nasa.gov/SEplot/SEplot1901/SE1935Jul30P.GIF... |
December 25 Solar eclipse of December 25, 1935 An annular solar eclipse occurred on December 25, 1935. This was the 5th solar eclipse in 1935, the maximum possible. The next time this will occur is 2206.-References:... |
---|---|---|---|---|
Partial (south) |
Partial (north) |
Partial (north) |
Partial (south) |
Annular (south) |
Saros 111 |
Saros 149 |
Saros 116 |
Saros 154 |
Saros 121 |
Final totality
Solar eclipses are seen on Earth because of a fortuitous combination of circumstances. Even on Earth, eclipses of the type familiar to people today are a temporary (on a geological time scale) phenomenon. Hundreds of millions of years in the past, the Moon was too close to the Earth to precisely occlude the Sun as it does during eclipses today; and many millions of years in the future, it will be too far away to do so.Due to tidal acceleration
, the orbit of the Moon around the Earth becomes approximately 3.8 cm more distant each year. It is estimated that in 600 million years, the distance from the Earth to the Moon will have increased by 23,500 km, meaning that it will no longer be able to completely cover the Sun's disk. This will be true even when the Moon is at perigee
, and the Earth at aphelion.
A complicating factor is that the Sun will increase in size over this timescale. This makes it even more unlikely that the Moon will be able to cause a total eclipse. Therefore, the last total solar eclipse on Earth will occur in slightly less than 600 million years.
Historical eclipses

(476–550) concluded the Heliocentric theory in solar eclipse. A solar eclipse of June 15, 763 BC mentioned in an Assyrian
text is important for the Chronology of the Ancient Orient. Also known as the eclipse of Bur Sagale, it is the earliest solar eclipse mentioned in historical sources that has been identified successfully. Perhaps the earliest still-unproven claim is that of archaeologist Bruce Masse asserting on the basis of several ancient flood myths
, which mention a total solar eclipse, he links an eclipse that occurred May 10, 2807 BC with a possible meteor impact
in the Indian Ocean
. There have been other claims to date earlier eclipses, notably that
of Mursili II
(likely 1312 BC), in Babylonia
, and also in China, during the Fifth Year (2084 BC) of the regime of Emperor Zhong Kang of Xia dynasty, but these are highly disputed and rely on much supposition.
Herodotus
wrote that Thales of Miletus
predicted an eclipse which occurred during a war between the Medians
and the Lydia
ns. Soldiers on both sides put down their weapons and declared peace as a result of the eclipse. Exactly which eclipse was involved has remained 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 in the middle of modern Turkey
.
An annular eclipse of the Sun occurred at Sardis
on February 17, 478 BC, while Xerxes was departing for his expedition against Greece
, as Herodotus recorded. Hind and Chambers considered this absolute date more than a century ago. Herodotus also reports that another solar eclipse was observed in Sparta
during the next year, on August 1, 477 BC. The sky suddenly darkened in the middle of the day, well after the battles of Thermopylae
and Salamis
, after the departure of Mardonius
to Thessaly
at the beginning of the spring of (477 BC) and his second attack on Athens
, after the return of Cleombrotus to Sparta
. The modern conventional dates are different by a year or two, and that these two eclipse records have been ignored so far. The Chronicle of Ireland recorded a solar eclipse on June 29, AD 512, and a solar eclipse was reported to have taken place during the Battle of Stiklestad
in July, 1030.
In the Indian epic the Mahabharata
the incident is related of the thirteenth day when Arjun vows to slay Jayadrath before nightfall, to avenge the death of Abhimanyu at Jayadratha's hands. What may only be described as a solar eclipse brought Jayadrath out to celebrate his surviving the day, only to have the sun reappear and Arjun killed Jayadrath. In the epic astronomers have calculated all possible eclipse pairs matching the above time difference and being visible from Kurukshetra
, the battlefield of the Mahabharata
war. 3129 BC and 2559 BC appear to be the best candidate for the Mahabharata war.
Attempts have been made to establish the exact date of Good Friday
by means of solar eclipses, but this research has not yielded conclusive results. Research has manifested the inability of total solar eclipses to serve as explanations for the recorded Good Friday
features of the crucifixion eclipse
. (Good Friday is recorded as being at Passover
, which is also recorded as being at or near the time of a full moon.)
The ancient Chinese astronomer Shi Shen
(fl. fourth century BC) was aware of the relation of the moon in a solar eclipse, as he provided instructions in his writing to predict them by using the relative positions of the moon and sun. The "radiating influence" theory for a solar eclipse (i.e., the moon's light was merely light reflected from the sun) was existent in Chinese thought from about the sixth century BC (in the Zhi Ran of Zhi Ni Zi), and opposed by the Chinese philosopher Wang Chong
(AD 27–97), who made clear in his writing that this theory was nothing new. This can be said of Jing Fang's writing in the 1st century BC, which stated:
The ancient Greeks had known this as well, since it was Parmenides
of Elea
, around 475 BC, who supported the theory of the moon shining because of reflected light, and was accepted in the time of Aristotle
as well. The Chinese astronomer and inventor Zhang Heng
(AD 78–139) wrote of both solar and lunar eclipse
s in the publication of Ling Xian in AD 120, supporting the radiating influence theory that Wang Chong had opposed (Wade-Giles
):
The later Chinese scientist and statesman Shen Kuo
(AD 1031–1095) also wrote of eclipses, and his reasoning for why the celestial bodies were round and spherical instead of flat (Wade-Giles
spelling):
Eclipses have been interpreted as omens, or portents, especially when associated with battles. On 22 January 1879
Zulu warriors successfully defeated a British battalion in the fight against imperialism during the Zulu War in South Africa. At 2:29 PM there was a solar eclipse. The conflict was named the Battle of Isandlwana
, the Zulu name for the battle translates as "the day of the dead moon".
Viewing
Looking directly at the photosphereof the Sun (the bright disk of the Sun itself), even for just a few seconds, can cause permanent damage to the retina
of the eye, because of the intense visible and invisible radiation that the photosphere emits. This damage can result in permanent 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.
Under normal conditions, the Sun is so bright that it is difficult to stare at it directly, so there is no tendency to look at it in a way that might damage the eye. However, during an eclipse, with so much of the Sun covered, it is easier and more tempting to stare at it. Unfortunately, looking at the Sun during an eclipse is just 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 in a fraction of a second.
Glancing at the Sun with all or most of its disk visible is unlikely to result in permanent harm, as the pupil will close down and reduce the brightness of the whole scene. If the eclipse is near total, the low average amount of light causes the pupil to open. Unfortunately the remaining parts of the Sun are still just as bright, so they are now brighter on the retina than when looking at a full Sun. As the eye has a small fovea, for detailed viewing, the tendency will be to track the image on to this best part of the retina, causing damage.
Partial and annular eclipses

removed from its case, a Compact Disc
, a black colour slide film, etc. must be avoided despite what may have been said in the media.
The safest way to view the Sun's disk is by indirect projection. 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 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. 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. 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, yet, depending on how much of the sun's disk is obscured, some darkening may be noticeable. If two-thirds 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.
Totality
It is safe to observe the total phase of a solar eclipse directly with the unaided eye, binoculars or a telescope, only when the Sun's photosphere is completely covered by the Moon. During this period the sun is too dim to be seen through filters. The Sun's faint coronawill be visible, and the chromosphere
, solar prominence
s, and possibly even a solar flare
may be seen. However, viewing the Sun after totality is dangerous.

will occur. These are caused by the sunlight still being able to reach Earth through lunar valleys, but no longer where mountains are present. Totality then begins with the diamond ring effect
, the last bright flash of sunlight.
At the end of totality, the same effects will occur in reverse order, and on the opposite side of the moon.
Photography
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 (70–200 mm for a 35 mm camera), and for the disk to fill most of the frame, a longer lens is needed (over 500 mm). As with viewing the sun directly, looking at it through the viewfinder of a cameracan produce damage to the retina, so care is advised.
Other observations

(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 prior to totality.
During a solar eclipse, special (indirect) observations can also be achieved with the unaided eye only. Normally the spots of light which fall through the small openings between the leaves of a tree have a circular shape. These are images of the Sun. During a partial eclipse, the light spots will show the partial shape of the Sun, as seen on the picture.
Another famous phenomenon is shadow bands
(also known as flying shadows), which are similar to shadows on the bottom of a swimming pool. They only occur just prior to and after totality, and are very difficult to observe. Many professional eclipse chasers have never been able to witness them.
During a partial eclipse, a related effect that can be seen is anisotropy in the shadows of objects. Particularly if the partial eclipse is nearly total, the unobscured part of the sun acts as an approximate line source of light. This means that objects cast shadows which have a very narrow penumbra in one direction, but a broad penumbra in the perpendicular direction.
1919 observations

helped to confirm Einstein
's theory of general relativity
. By comparing the apparent distance between two stars, with and without the Sun between them, Arthur Eddington stated that the theoretical predictions
about gravitational lens
es were confirmed, though it now appears the data was ambiguous at the time. The observation with the Sun between the stars was only possible during totality, since the stars are then visible.
Gravity anomalies
There is a long history of observations of gravity-related phenomena during solar eclipses, especially around totality. In 1954 and again in 1959, Maurice Allaisreported observations of strange and unexplained movement during solar eclipses. This phenomenon is now called the Allais Effect
. Similarly, Saxl and Allen in 1970 observed sudden change in motion of a torsion pendulum, and this phenomenon is called
the Saxl effect.
A recent published observation during the 1997 solar eclipse by Wang et al. suggested a possible gravitational shielding effect, though there is some serious debate. Later in 2002, Yang and Wang published detailed data analysis which suggested that the phenomenon still remains unexplained. More studies are being planned by NASA and ESA over the next decade.
Before sunrise, after sunset
The phenomenon of atmospheric refractionmakes it possible to observe the Sun (and hence a solar eclipse) even when it is slightly below the horizon. It is, however, possible for a solar eclipse to attain totality (or in the event of a partial eclipse, near-totality) before (visual and actual) sunrise or after sunset from a particular location. When this occurs shortly before the former or after the latter, the sky will appear much darker than it would otherwise be immediately before sunrise or after sunset. On these occasions, an object (especially a planet
, often Mercury
) may be visible near the sunrise or sunset point of the horizon when it could not have been seen without the eclipse.
Eclipses and transits
In principle, the simultaneous occurrence of a Solar eclipse and a 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 Mercurywill be on July 5, 6757, and a Solar eclipse and a transit of Venus
is expected on April 5, 15232.
Only five hours after the transit of Venus on June 4, 1769, there was a total solar eclipse, which was visible in Northern America, Europe, and Northern Asia as partial solar eclipse. This was the lowest time difference between a transit of a planet and a solar eclipse in the historical past.
More common, but still infrequent, is a conjunction of any planet (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) even closer to the Sun than Mercury; the only way to confirm its existence would have been to observe it during a total solar eclipse. It now is known that no such planet exists. While there does remain some possibility for small Vulcanoid asteroids to exist, none has ever been found.
Artificial satellites

, for example, an object would need to be about 3.35 km (2.08 mi) 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.
Artificial satellites do play an important role in documenting solar eclipses. Images of the umbra on the Earth's surface taken from Mir
and the International Space Station are among the most spectacular of all eclipse images. Observations of eclipses from satellites orbiting above the Earth's atmosphere are not subject to weather conditions.
The direct observation of a total solar eclipse from space is rare. The only documented case is Gemini 12
in 1966. The partial phase of the 2006 total eclipse was visible from the International Space Station. At first, it looked as though an orbit correction in the middle of March would bring the ISS in the path of totality, but this correction was postponed.
Meteorological measurements
A marked drop of the intensity of the solar radiation occurs during solar eclipse. It influences the actions in the atmosphere. The variations of the atmospheric actions display in changes of standard meteorological and physical quantities
. These may be noticed by a measurement of the air temperature and other meteorological quantities (e.g.: air humidity, soil temperature, colour of the solar radiation).
The progressions of the quantities are usually detected by special weather station
s because of a short duration of a total (annular) solar eclipse. The properties of the devices usually are: high speed of measurement, high resolution, and sensitivity. Acquired results show variations in progressions of meteorological and physical quantities (e.g.: colour of the light).
Recent and forthcoming solar eclipses
Short term eclipse cycles repeat every six lunations (every 177 days), each set lasting three–four years. They occur at either the ascending or descending node of the moon's orbit. Each set has the moon's shadow crossing the earth near the north or south pole, and subsequent events progress toward the other pole until it misses the earth and the series ends. The Saros cycle
increments by 5 within each set, and 5 different sets repeat every 18 years, the Saros period.
1997–2000
2000–2003
2004–2007
2008–2011
2011–2014
2015–2018
2018–2021
2022–2025
Eclipses elsewhere
- Solar eclipses on JupiterSolar eclipses on JupiterSolar eclipses on Jupiter occur when any of the natural satellites of Jupiter pass in front of the Sun as seen from the planet Jupiter. For bodies which appear smaller in angular diameter than the Sun, the proper term would be a transit...
- Solar eclipses on SaturnSolar eclipses on SaturnSolar eclipses on Saturn occur when the natural satellites of Saturn pass in front of the Sun as seen from Saturn. For bodies which appear smaller in angular diameter than the Sun, the proper term would be a transit. For bodies which are larger than the apparent size of the Sun, the proper term...
- Solar eclipses on Uranus and NeptuneSolar eclipses on Uranus and NeptuneSolar eclipses on Uranus and Neptune occur when any of the natural satellites of both Uranus and Neptune pass in front of the Sun as seen from both planets. For bodies which appear smaller in angular diameter than the Sun, the proper term would be a transit...
- Solar eclipses on PlutoSolar eclipses on PlutoSolar eclipses on Pluto are caused when one of its four natural satellites – Charon, Nix, Hydra, and P4 – passes in front of the Sun, blocking its light....
- Transit of Deimos from MarsTransit of Deimos from MarsA transit of Deimos across the Sun as seen from Mars takes place when Deimos passes directly between the Sun and a point on the surface of Mars, obscuring a small part of the Sun's disc for an observer on Mars...
- Transit of Phobos from MarsTransit of Phobos from MarsA transit of Phobos across the Sun as seen from Mars takes place when Phobos passes directly between the Sun and a point on the surface of Mars, obscuring a large part of the Sun's disc for an observer on Mars. During a transit, Phobos can be seen from Mars as a large black disc rapidly moving...
Eclipse lists
Articles on individual solar eclipsesMiscellaneous
- Besselian ElementsBesselian ElementsThe Besselian Elements are schedular values to calculate and predict the local circumstances of occultations for an observer on Earth. This method is particularly used for solar eclipses but also applied for occultations of stars or planets by the Moon and transits of Venus or Mercury...
- Black Sun (mythology)Black Sun (mythology)The Black Sun in Mesoamerican mythology has many mystical meanings, among them it is connected to the god Quetzalcoatl and his penetration in the Underworld through the west door after his diurnal passage on the sky. Amidst the Mexicas there were two suns, the young day sun and the ancient sun,...
- Solar eclipses in fictionSolar eclipses in fictionThis is a list of fictional stories in which solar eclipses feature as an important plot element. Mere passing mentions are not listed.- Novels :* Dating of the Mahabharata with the help of a solar eclipse....
External links
- Solar eclipse of January 15, 2010, Fred EspenakFred EspenakFred Espenak is an American astrophysicist. He works at the Goddard Space Flight Center. He is best known for his work on eclipse predictions....
, NASA - Detailed eclipse explanations and predictions, Hermit Eclipse
- Prof. Druckmüller's eclipse photography site
- World Atlas of Solar Eclipse Paths, Fred Espenak (archived from the original on 2010-05027)
- Solar eclipse time sequence
- NASA's Eclipse Home Page, Fred Espenak (archived from the original on 2010-05-27)
- Animated maps of past and future solar eclipses
- Search among the 11,898 solar eclipses over five millennium and display interactive maps
- Looking Back at an Eclipsed Earth 1999 August 11 from MirMirMir was a space station operated in low Earth orbit from 1986 to 2001, at first by the Soviet Union and then by Russia. Assembled in orbit from 1986 to 1996, Mir was the first modular space station and had a greater mass than that of any previous spacecraft, holding the record for the...
EO-27 - Astronomy Picture of the DayAstronomy Picture of the DayAstronomy Picture of the Day is a website provided by NASA and Michigan Technological University . According to the website, "Each day a different image or photograph of our universe is featured, along with a brief explanation written by a professional astronomer."The photograph is not necessarily...
10 June 2007 - Animated explanation of the mechanics of a solar eclipse, University of Glamorgan
Eye safety
- Eye Safety During Solar Eclipses, F. Espenak (NASA Goddard Space Flight CenterGoddard Space Flight CenterThe Goddard Space Flight Center is a major NASA space research laboratory established on May 1, 1959 as NASA's first space flight center. GSFC employs approximately 10,000 civil servants and contractors, and is located approximately northeast of Washington, D.C. in Greenbelt, Maryland, USA. GSFC,...
) - How to Watch a Partial Solar Eclipse Safely, A. M. MacRobert (Sky & Telescope magazine)
- UK hospitals assess eye damage after solar eclipse, British Medical Journal, August 21, 1999, p. 319–469