Eclipse

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Totality during the 1999 solar eclipse. Solar prominences can be seen along the limb (in red) as well as extensive coronal filaments. Solar eclipse 1999 4.jpg
Totality during the 1999 solar eclipse. Solar prominences can be seen along the limb (in red) as well as extensive coronal filaments.
The shadow of an eclipse on Earth as seen from space ISS-52 Eclipse 2017 Umbra Viewed from Space (1).jpg
The shadow of an eclipse on Earth as seen from space

An eclipse is an astronomical event which occurs when an astronomical object or spacecraft is temporarily obscured, by passing into the shadow of another body or by having another body pass between it and the viewer. This alignment of three celestial objects is known as a syzygy. [1] An eclipse is the result of either an occultation (completely hidden) or a transit (partially hidden). A "deep eclipse" (or "deep occultation") is when a small astronomical object is behind a bigger one. [2] [3]

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The term eclipse is most often used to describe either a solar eclipse, when the Moon's shadow crosses the Earth's surface, or a lunar eclipse, when the Moon moves into the Earth's shadow. However, it can also refer to such events beyond the Earth–Moon system: for example, a planet moving into the shadow cast by one of its moons, a moon passing into the shadow cast by its host planet, or a moon passing into the shadow of another moon. A binary star system can also produce eclipses if the plane of the orbit of its constituent stars intersects the observer's position.

For the special cases of solar and lunar eclipses, these only happen during an "eclipse season", the two times of each year when the plane of the Earth's orbit around the Sun crosses with the plane of the Moon's orbit around the Earth and the line defined by the intersecting planes points near the Sun. The type of solar eclipse that happens during each season (whether total, annular, hybrid, or partial) depends on apparent sizes of the Sun and Moon. If the orbit of the Earth around the Sun and the Moon's orbit around the Earth were both in the same plane with each other, then eclipses would happen every month. There would be a lunar eclipse at every full moon, and a solar eclipse at every new moon. It is because of the non-planar differences that eclipses are not a common event. If both orbits were perfectly circular, then each eclipse would be the same type every month.

Lunar eclipses can be viewed from the entire nightside half of the Earth. But solar eclipses, particularly total eclipses occurring at any one particular point on the Earth's surface, are very rare events that can be many decades apart.

Etymology

The term is derived from the ancient Greek noun ἔκλειψις (ékleipsis), which means 'the abandonment', 'the downfall', or 'the darkening of a heavenly body', which is derived from the verb ἐκλείπω (ekleípō) which means 'to abandon', 'to darken', or 'to cease to exist', [4] a combination of prefix ἐκ- (ek-), from preposition ἐκ (ek), 'out', and of verb λείπω (leípō), 'to be absent'. [5] [6]

Umbra, penumbra and antumbra

Umbra, penumbra and antumbra cast by an opaque object occulting a larger light source Umbra01.svg
Umbra, penumbra and antumbra cast by an opaque object occulting a larger light source

For any two objects in space, a line can be extended from the first through the second. The latter object will block some amount of light being emitted by the former, creating a region of shadow around the axis of the line. Typically these objects are moving with respect to each other and their surroundings, so the resulting shadow will sweep through a region of space, only passing through any particular location in the region for a fixed interval of time. As viewed from such a location, this shadowing event is known as an eclipse. [7]

Typically the cross-section of the objects involved in an astronomical eclipse is roughly disk-shaped. [7] The region of an object's shadow during an eclipse is divided into three parts: [8]

Sun-Moon configurations that produce a total (A), annular (B), and partial (C) solar eclipse Solar eclipse types.svg
Sun-Moon configurations that produce a total (A), annular (B), and partial (C) solar eclipse

A total eclipse occurs when the observer is within the umbra, an annular eclipse when the observer is within the antumbra, and a partial eclipse when the observer is within the penumbra. During a lunar eclipse only the umbra and penumbra are applicable, because the antumbra of the Sun-Earth system lies far beyond the Moon. Analogously, Earth's apparent diameter from the viewpoint of the Moon is nearly four times that of the Sun and thus cannot produce an annular eclipse. The same terms may be used analogously in describing other eclipses, e.g., the antumbra of Deimos crossing Mars, or Phobos entering Mars's penumbra.

The first contact occurs when the eclipsing object's disc first starts to impinge on the light source; second contact is when the disc moves completely within the light source; third contact when it starts to move out of the light; and fourth or last contact when it finally leaves the light source's disc entirely.

For spherical bodies, when the occulting object is smaller than the star, the length (L) of the umbra's cone-shaped shadow is given by:

where Rs is the radius of the star, Ro is the occulting object's radius, and r is the distance from the star to the occulting object. For Earth, on average L is equal to 1.384×106  km, which is much larger than the Moon's semimajor axis of 3.844×105 km. Hence the umbral cone of the Earth can completely envelop the Moon during a lunar eclipse. [9] If the occulting object has an atmosphere, however, some of the luminosity of the star can be refracted into the volume of the umbra. This occurs, for example, during an eclipse of the Moon by the Earth—producing a faint, ruddy illumination of the Moon even at totality.

On Earth, the shadow cast during an eclipse moves very approximately at 1 km per sec. This depends on the location of the shadow on the Earth and the angle in which it is moving. [10]

Eclipse cycles

As the Earth revolves around the Sun, approximate axial parallelism of the Moon's tilted orbital plane (inclined at five degrees to the Earth's orbital plane) results in the revolution of the lunar nodes relative to the 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. Eclipse vs new or full moons, annotated.svg
As the Earth revolves around the Sun, approximate axial parallelism of the Moon's tilted orbital plane (inclined at five degrees to the Earth's orbital plane) results in the revolution of the lunar nodes relative to the 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.

An eclipse cycle takes place when eclipses in a series are separated by a certain interval of time. This happens when the orbital motions of the bodies form repeating harmonic patterns. A particular instance is the saros, which results in a repetition of a solar or lunar eclipse every 6,585.3 days, or a little over 18 years. Because this is not a whole number of days, successive eclipses will be visible from different parts of the world. [11] In one saros period there are 239.0 anomalistic periods, 241.0 sidereal periods, 242.0 nodical periods, and 223.0 synodic periods. Although the orbit of the Moon does not give exact integers, the numbers of orbit cycles are close enough to integers to give strong similarity for eclipses spaced at 18.03 yr intervals.

Earth–Moon system

A symbolic orbital diagram from the view of the Earth at the center, with the Sun and Moon projected upon the celestial sphere, showing the Moon's two nodes where eclipses can occur. Lunar eclipse diagram-en.svg
A symbolic orbital diagram from the view of the Earth at the center, with the Sun and Moon projected upon the celestial sphere, showing the Moon's two nodes where eclipses can occur.

An eclipse involving the Sun, Earth, and Moon can occur only when they are nearly in a straight line, allowing one to be hidden behind another, viewed from the third. Because the orbital plane of the Moon is tilted with respect to the orbital plane of the Earth (the ecliptic), eclipses can occur only when the Moon is close to the intersection of these two planes (the nodes). The Sun, Earth and nodes are aligned twice a year (during an eclipse season), and eclipses can occur during a period of about two months around these times. There can be from four to seven eclipses in a calendar year, which repeat according to various eclipse cycles, such as a saros.

Between 1901 and 2100 there are the maximum of seven eclipses in: [12]

Excluding penumbral lunar eclipses, there are a maximum of seven eclipses in: [13]

Solar eclipse

Ten Minute Time Lapse Video of the Total Solar Eclipse on April 8, 2024, in Mazatlán, Mexico.
The progression of a solar eclipse on August 1, 2008, viewed from Novosibirsk, Russia. The time between shots is three minutes. 2008-08-01 Solar eclipse progression with timestamps.jpg
The progression of a solar eclipse on August 1, 2008, viewed from Novosibirsk, Russia. The time between shots is three minutes.

As observed from the Earth, a solar eclipse occurs when the Moon passes in front of the Sun. The type of solar eclipse event depends on the distance of the Moon from the Earth during the event. A total solar eclipse occurs when the Earth intersects the umbra portion of the Moon's shadow. When the umbra does not reach the surface of the Earth, the Sun is only partially occulted, resulting in an annular eclipse. Partial solar eclipses occur when the viewer is inside the penumbra. [14]

Each icon shows the view from the centre of its black spot, representing the Moon (not to scale) Solar eclipse visualisation.svg
Each icon shows the view from the centre of its black spot, representing the Moon (not to scale)

The eclipse magnitude is the fraction of the Sun's diameter that is covered by the Moon. For a total eclipse, this value is always greater than or equal to one. In both annular and total eclipses, the eclipse magnitude is the ratio of the angular sizes of the Moon to the Sun. [15]

Solar eclipses are relatively brief events that can only be viewed in totality along a relatively narrow track. Under the most favorable circumstances, a total solar eclipse can last for 7 minutes, 31 seconds, and can be viewed along a track that is up to 250 km wide. However, the region where a partial eclipse can be observed is much larger. The Moon's umbra will advance eastward at a rate of 1,700 km/h, until it no longer intersects the Earth's surface.

Geometry of a total solar eclipse (not to scale) Geometry of a Total Solar Eclipse.svg
Geometry of a total solar eclipse (not to scale)

During a solar eclipse, the Moon can sometimes perfectly cover the Sun because its apparent size is nearly the same as the Sun's when viewed from the Earth. A total solar eclipse is in fact an occultation while an annular solar eclipse is a transit.

When observed at points in space other than from the Earth's surface, the Sun can be eclipsed by bodies other than the Moon. Two examples include when the crew of Apollo 12 observed the Earth to eclipse the Sun in 1969 and when the Cassini probe observed Saturn to eclipse the Sun in 2006.

The progression of a lunar eclipse from right to left. Totality is shown with the first two images. These required a longer exposure time to make the details visible. Eclipse lune.jpg
The progression of a lunar eclipse from right to left. Totality is shown with the first two images. These required a longer exposure time to make the details visible.

Lunar eclipse

Lunar eclipses occur when the Moon passes through the Earth's shadow. This happens only during a full moon, when the Moon is on the far side of the Earth from the Sun. Unlike a solar eclipse, an eclipse of the Moon can be observed from nearly an entire hemisphere. For this reason it is much more common to observe a lunar eclipse from a given location. A lunar eclipse lasts longer, taking several hours to complete, with totality itself usually averaging anywhere from about 30 minutes to over an hour. [16]

There are three types of lunar eclipses: penumbral, when the Moon crosses only the Earth's penumbra; partial, when the Moon crosses partially into the Earth's umbra; and total, when the Moon crosses entirely into the Earth's umbra. Total lunar eclipses pass through all three phases. Even during a total lunar eclipse, however, the Moon is not completely dark. Sunlight refracted through the Earth's atmosphere enters the umbra and provides a faint illumination. Much as in a sunset, the atmosphere tends to more strongly scatter light with shorter wavelengths, so the illumination of the Moon by refracted light has a red hue, [17] thus the phrase 'Blood Moon' is often found in descriptions of such lunar events as far back as eclipses are recorded. [18]

Historical record

This print shows Parisians watching the solar eclipse of July 28, 1851 Les parisiens pendant l'eclipse du 28 Juillet.jpg
This print shows Parisians watching the solar eclipse of July 28, 1851

Records of solar eclipses have been kept since ancient times. Eclipse dates can be used for chronological dating of historical records. A Syrian clay tablet, in the Ugaritic language, records a solar eclipse which occurred on March 5, 1223, B.C., [19] while Paul Griffin argues that a stone in Ireland records an eclipse on November 30, 3340 B.C. [20] Positing classical-era astronomers' use of Babylonian eclipse records mostly from the 13th century BC provides a feasible and mathematically consistent [21] explanation for the Greek finding all three lunar mean motions (synodic, anomalistic, draconitic) to a precision of about one part in a million or better. Chinese historical records of solar eclipses date back over 3,000 years and have been used to measure changes in the Earth's rate of spin. [22]

The first person to give scientific explanation on eclipses was Anaxagoras [c500BC - 428BC]. [23] Anaxagoras stated that the Moon shines by reflected light from the Sun. [24]

In 5th century AD, solar and lunar eclipses were scientifically explained by Aryabhata, in his treatise Aryabhatiya. [25] Aryabhata states that the Moon and planets shine by reflected sunlight and explains eclipses in terms of shadows cast by and falling on Earth. Aryabhata provides the computation and the size of the eclipsed part during an eclipse. Indian computations were very accurate that 18th-century French scientist Guillaume Le Gentil, during a visit to Pondicherry, India, found the Indian computations of the duration of the lunar eclipse of 30 August 1765 to be short by only 41 seconds, whereas Le Gentil's charts were long by 68 seconds.

By the 1600s, European astronomers were publishing books with diagrams explaining how lunar and solar eclipses occurred. [26] [27] In order to disseminate this information to a broader audience and decrease fear of the consequences of eclipses, booksellers printed broadsides explaining the event either using the science or via astrology. [28]

Eclipses in mythology and religion

The American author Gene Weingarten described the tension between belief and eclipses thus: "I am a devout atheist but can't explain why the moon is exactly the right size, and gets positioned so precisely between the Earth and the sun, that total solar eclipses are perfect. It bothers me." [29]

The Graeco-Roman historian Cassius Dio, writing between AD 211-229, relates the anecdote that Emperor Claudius considered it necessary to prevent disturbance among the Roman population by publishing a prediction for a solar eclipse which would fall on his birthday anniversary [1 August in the year AD 45]. In this context, Cassius Dio provides a detailed explanation of solar and lunar eclipses. [30]

Typically in mythology, eclipses were understood to be one variation or another of a spiritual battle between the sun and evil forces or spirits of darkness. [31] More specifically, in Norse mythology, it is believed that there is a wolf by the name of Fenrir that is in constant pursuit of the Sun, and eclipses are thought to occur when the wolf successfully devours the divine Sun. [32] [ failed verification ] Other Norse tribes believe that there are two wolves by the names of Sköll and Hati that are in pursuit of the Sun and the Moon, known by the names of Sol and Mani, and these tribes believe that an eclipse occurs when one of the wolves successfully eats either the Sun or the Moon. [33]

In most types of mythologies and certain religions, eclipses were seen as a sign that the gods were angry and that danger was soon to come, so people often altered their actions in an effort to dissuade the gods from unleashing their wrath. In the Hindu religion, for example, people often sing religious hymns for protection from the evil spirits of the eclipse, and many people of the Hindu religion refuse to eat during an eclipse to avoid the effects of the evil spirits. [34] Hindu people living in India will also wash off in the Ganges River, which is believed to be spiritually cleansing, directly following an eclipse to clean themselves of the evil spirits. [34] In early Judaism and Christianity, eclipses were viewed as signs from God, and some eclipses were seen as a display of God's greatness or even signs of cycles of life and death. [34] However, more ominous eclipses such as a blood moon were believed to be a divine sign that God would soon destroy their enemies. [34]

Other planets and dwarf planets

Gas giants

A picture of Jupiter and its moon Io taken by Hubble. The black spot is Io's shadow. JupiterandIo.jpg
A picture of Jupiter and its moon Io taken by Hubble. The black spot is Io's shadow.
Saturn occults the Sun as seen from the Cassini-Huygens space probe Saturn eclipse.jpg
Saturn occults the Sun as seen from the Cassini–Huygens space probe

The gas giant planets have many moons and thus frequently display eclipses. The most striking involve Jupiter, which has four large moons and a low axial tilt, making eclipses more frequent as these bodies pass through the shadow of the larger planet. Transits occur with equal frequency. It is common to see the larger moons casting circular shadows upon Jupiter's cloudtops.

The eclipses of the Galilean moons by Jupiter became accurately predictable once their orbital elements were known. During the 1670s, it was discovered that these events were occurring about 17 minutes later than expected when Jupiter was on the far side of the Sun. Ole Rømer deduced that the delay was caused by the time needed for light to travel from Jupiter to the Earth. This was used to produce the first estimate of the speed of light. [35]

The timing of the Jovian satellite eclipses was also used to calculate an observer's longitude upon the Earth. By knowing the expected time when an eclipse would be observed at a standard longitude (such as Greenwich), the time difference could be computed by accurately observing the local time of the eclipse. The time difference gives the longitude of the observer because every hour of difference corresponded to 15° around the Earth's equator. This technique was used, for example, by Giovanni D. Cassini in 1679 to re-map France. [36]

On the other three gas giants (Saturn, Uranus and Neptune) eclipses only occur at certain periods during the planet's orbit, due to their higher inclination between the orbits of the moon and the orbital plane of the planet. The moon Titan, for example, has an orbital plane tilted about 1.6° to Saturn's equatorial plane. But Saturn has an axial tilt of nearly 27°. The orbital plane of Titan only crosses the line of sight to the Sun at two points along Saturn's orbit. As the orbital period of Saturn is 29.7 years, an eclipse is only possible about every 15 years.

Mars

Transit of Phobos from Mars, as seen by the Mars Opportunity rover (10 March 2004). PIA05553.gif
Transit of Phobos from Mars, as seen by the Mars Opportunity rover (10 March 2004).

On Mars, only partial solar eclipses (transits) are possible, because neither of its moons is large enough, at their respective orbital radii, to cover the Sun's disc as seen from the surface of the planet. Eclipses of the moons by Mars are not only possible, but commonplace, with hundreds occurring each Earth year. There are also rare occasions when Deimos is eclipsed by Phobos. [37] Martian eclipses have been photographed from both the surface of Mars and from orbit.

Pluto

Pluto, with its proportionately largest moon Charon, is also the site of many eclipses. A series of such mutual eclipses occurred between 1985 and 1990. [38] These daily events led to the first accurate measurements of the physical parameters of both objects. [39]

Mercury and Venus

Eclipses are impossible on Mercury and Venus, which have no moons. However, as seen from the Earth, both have been observed to transit across the face of the Sun. Transits of Venus occur in pairs separated by an interval of eight years, but each pair of events happen less than once a century. [40] According to NASA, the next pair of Venus transits will occur on December 10, 2117, and December 8, 2125. Transits of Mercury are much more common, occurring 13 times each century, on average. [41]

Eclipsing binaries

A binary star system consists of two stars that orbit around their common centre of mass. The movements of both stars lie on a common orbital plane in space. When this plane is very closely aligned with the location of an observer, the stars can be seen to pass in front of each other. The result is a type of extrinsic variable star system called an eclipsing binary.

The maximum luminosity of an eclipsing binary system is equal to the sum of the luminosity contributions from the individual stars. When one star passes in front of the other, the luminosity of the system is seen to decrease. The luminosity returns to normal once the two stars are no longer in alignment. [42]

The first eclipsing binary star system to be discovered was Algol, a star system in the constellation Perseus. Normally this star system has a visual magnitude of 2.1. However, every 2.867 days the magnitude decreases to 3.4 for more than nine hours. This is caused by the passage of the dimmer member of the pair in front of the brighter star. [43] The concept that an eclipsing body caused these luminosity variations was introduced by John Goodricke in 1783. [44]

Types

Sun – Moon – Earth: Solar eclipse | annular eclipse | hybrid eclipse | partial eclipse

Sun – Earth – Moon: Lunar eclipse | penumbral eclipse | partial lunar eclipse | central lunar eclipse

Sun – Phobos – Mars: Transit of Phobos from Mars | Solar eclipses on Mars

Sun – Deimos – Mars: Transit of Deimos from Mars | Solar eclipses on Mars

Other types: Solar eclipses on Jupiter | Solar eclipses on Saturn | Solar eclipses on Uranus | Solar eclipses on Neptune | Solar eclipses on Pluto

See also

Related Research Articles

<span class="mw-page-title-main">Lunar eclipse</span> Astronomical event

A lunar eclipse is an astronomical event that occurs when the Moon moves into the Earth's shadow, causing the Moon to be darkened. Such an alignment occurs during an eclipse season, approximately every six months, during the full moon phase, when the Moon's orbital plane is closest to the plane of the Earth's orbit.

<span class="mw-page-title-main">Conjunction (astronomy)</span> When two astronomical objects have the same right ascension or the same ecliptic longitude

In astronomy, a conjunction occurs when two astronomical objects or spacecraft appear to be close to each other in the sky. This means they have either the same right ascension or the same ecliptic longitude, usually as observed from Earth.

<span class="mw-page-title-main">Umbra, penumbra and antumbra</span> Distinct parts of a shadow


The umbra, penumbra and antumbra are three distinct parts of a shadow, created by any light source after impinging on an opaque object. Assuming no diffraction, for a collimated beam of light, only the umbra is cast.

<span class="mw-page-title-main">Shadow</span> Area where light is blocked by an object

A shadow is a dark area where light from a light source is blocked by an object. It occupies all of the three-dimensional volume behind an object with light in front of it. The cross section of a shadow is a two-dimensional silhouette, or a reverse projection of the object blocking the light.

<span class="mw-page-title-main">Extraterrestrial sky</span> Extraterrestrial view of outer space

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<span class="mw-page-title-main">Solar eclipses on Jupiter</span> When moons of Jupiter pass before the Sun

Solar eclipses on Jupiter occur when any of the natural satellites of Jupiter pass in front of the Sun as seen from the planet Jupiter.

<span class="mw-page-title-main">Magnitude of eclipse</span> Fraction of the diameter of the eclipsed body which is in eclipse

The magnitude of eclipse is the fraction of the angular diameter of a celestial body being eclipsed. This applies to all celestial eclipses. The magnitude of a partial or annular solar eclipse is always between 0.0 and 1.0, while the magnitude of a total solar eclipse is always greater than or equal to 1.0, and has a theoretically maximum value of around 1.12.

<span class="mw-page-title-main">Solar eclipse</span> Natural phenomenon wherein the Sun is obscured by the Moon

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 the plane of Earth's orbit. In a total eclipse, the disk of the Sun is fully obscured by the Moon. In 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.

<span class="mw-page-title-main">Solar eclipses on Mars</span> When moons of Mars pass before the Sun

The two moons of Mars, Phobos and Deimos, are much smaller than Earth's Moon, greatly reducing the frequency of solar eclipses on that planet. Neither moon's apparent diameter is large enough to cover the disk of the Sun, and therefore they are annular solar eclipses and can also be considered transits.

<span class="mw-page-title-main">February 2008 lunar eclipse</span> Total lunar eclipse of 20 February 2008

A total lunar eclipse occurred on February 20 and February 21, 2008. It was visible in the eastern evening sky on February 20 for all of North and South America, and on February 21 in the predawn western sky from most of Africa and Europe. Greatest Eclipse occurring on Thursday, February 21, 2008, at 03:26:03 UTC, totality lasting 49 minutes and 45.6 seconds.

<span class="mw-page-title-main">April 2014 lunar eclipse</span> Total lunar eclipse in April 2014

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<span class="mw-page-title-main">October 2014 lunar eclipse</span> Total lunar eclipse of 8 October 2014

A total lunar eclipse took place on Wednesday 8 October 2014. It is the second of two total lunar eclipses in 2014, and the second in a tetrad. Other eclipses in the tetrad are those of 15 April 2014, 4 April 2015, and 28 September 2015. Occurring only 2.1 days after perigee, the Moon's apparent diameter was larger, 1960.6 arcseconds.

A partial lunar eclipse took place on Saturday, June 25, 1983, the first of two lunar eclipses in 1983 with an umbral eclipse magnitude of 0.33479. A partial lunar eclipse happens when the Earth moves between the Sun and the Full Moon, but they are not precisely aligned. Only part of the Moon's visible surface moves into the dark part of the Earth's shadow. A partial lunar eclipse occurs when the Earth moves between the Sun and Moon but the three celestial bodies do not form a straight line in space. When that happens, a small part of the Moon's surface is covered by the darkest, central part of the Earth's shadow, called the umbra. The rest of the Moon is covered by the outer part of the Earth's shadow called the penumbra. The Earth's shadow on the moon was clearly visible in this eclipse, with 33% of the Moon in shadow; the partial eclipse lasted for 2 hours and 15 minutes.

A partial lunar eclipse occurred on Tuesday, July 25, 1972 and Wednesday, July 26, 1972, the second of two lunar eclipses in 1972 with an umbral eclipse magnitude of 0.54271. A partial lunar eclipse occurs when the Earth moves between the Sun and Moon but the three celestial bodies do not form a straight line in space. When that happens, a small part of the Moon's surface is covered by the darkest, central part of the Earth's shadow, called the umbra. The rest of the Moon is covered by the outer part of the Earth's shadow called the penumbra. The moon's apparent diameter was 3.2 arcseconds smaller than the January 30, 1972 lunar eclipse.

<span class="mw-page-title-main">June 1955 lunar eclipse</span> Penumbral lunar eclipse June 5, 1955

A penumbral lunar eclipse took place at the Moon's ascending of the orbit on Sunday, June 5, 1955, with a penumbral eclipse magnitude of 0.62181 (62.181%). A penumbral lunar eclipse takes place when the Moon moves through the faint, outer part of Earth's shadow, the penumbra. This type of eclipse is not as dramatic as other types of lunar eclipses and is often mistaken for a regular Full Moon. The Moon shines because its surface reflects the Sun's rays. A lunar eclipse happens when the Earth comes between the Sun and the Moon and blocks some or all of the Sun's light from reaching the Moon. A penumbral lunar eclipse occurs when the Sun, Earth, and the Moon are imperfectly aligned. When this happens, the Earth blocks some of the Sun's light from directly reaching the Moon's surface and covers all or part of the Moon with the outer part of its shadow, also known as the penumbra. Since the penumbra is much fainter than the dark core of the Earth's shadow, the umbra, a penumbral eclipse of the Moon is often difficult to tell apart from a normal Full Moon. Occurring only 0.5 days after apogee, the moon's apparent diameter was 6.5% smaller than average.

<span class="mw-page-title-main">Gamma (eclipse)</span> Measure of the alignment of an eclipse

Gamma of an eclipse describes how centrally the shadow of the Moon or Earth strikes the other body. This distance, measured at the moment when the axis of the shadow cone passes closest to the center of the Earth or Moon, is stated as a fraction of the equatorial radius of the Earth or Moon.

<span class="mw-page-title-main">Solar eclipse of May 20, 2012</span> 21st-century annular solar eclipse

The solar eclipse of May 20, 2012 was an annular solar eclipse that was visible in a band spanning through Eastern Asia, the Pacific Ocean, and North America. As a partial solar eclipse, it was visible from northern Greenland to Hawaii, and from eastern Indonesia at sunrise to northwestern Mexico at sunset. The moon's apparent diameter was smaller because the eclipse was occurring only 32 1/2 hours after apogee.

<span class="mw-page-title-main">Syzygy (astronomy)</span> Alignment of celestial bodies

In astronomy, a syzygy is a roughly straight-line configuration of three or more celestial bodies in a gravitational system.

<span class="mw-page-title-main">Solar eclipses on Saturn</span> When moons of Saturn pass before the Sun

Solar eclipses on Saturn occur when the natural satellites of Saturn pass in front of the Sun as seen from Saturn. These eclipses happen fairly often. For example, some of Saturn's moons can have a solar eclipse every day depending on the saturnian season.

<span class="mw-page-title-main">Solar eclipses on the Moon</span> Lunar phenomenon wherein the Sun is obscured by Earth

Solar eclipses on the Moon are caused when the planet Earth passes in front of the Sun and blocks its light. Viewers on Earth experience a lunar eclipse during a solar eclipse on the Moon.

References

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  7. 1 2 Westfall, John; Sheehan, William (2014), Celestial Shadows: Eclipses, Transits, and Occultations, Astrophysics and Space Science Library, vol. 410, Springer, pp. 1–5, ISBN   978-1493915354.
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  18. ↑ Ancient Timekeepers, "Ancient Timekeepers, Part 1: Movements of the Earth". 2011-09-16. Archived from the original on 2011-10-26. Retrieved 2011-10-25.
  19. ↑ de Jong, T.; van Soldt, W. H. (1989). "The earliest known solar eclipse record redated". Nature. 338 (6212): 238–240. Bibcode:1989Natur.338..238D. doi:10.1038/338238a0. S2CID   186243477. The new translation runs as follows: (Obverse) "On the ... day of the new moon in [the month] ḫiyaru the Sun went down, its gate-keeper was Ršp". (Reverse) "Two livers were examined: danger". [...] As pointed out by Sawyer and Stephenson, Ršp is probably to be identified with the planet Mars. [...] Of the candidate eclipses [...], the one occurring on 5 March 1223 BC is the only one during which the plant Mars was above the horizon.
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  21. ↑ See DIO 16 Archived 2011-07-26 at the Wayback Machine p.2 (2009). Though those Greek and perhaps Babylonian astronomers who determined the three previously unsolved lunar motions were spread over more than four centuries (263 BC to 160 AD), the math-indicated early eclipse records are all from a much smaller span Archived 2015-04-02 at the Wayback Machine : the 13th century BC. The anciently attested Greek technique: use of eclipse cycles, automatically providing integral ratios, which is how all ancient astronomers' lunar motions were expressed. Long-eclipse-cycle-based reconstructions precisely produce all of the 24 digits appearing in the three attested ancient motions just cited: 6247 synod = 6695 anom (System A), 5458 synod = 5923 drac (Hipparchos), 3277 synod = 3512 anom (Planetary Hypotheses). By contrast, the System B motion, 251 synod = 269 anom (Aristarchos?), could have been determined without recourse to remote eclipse data, simply by using a few eclipse-pairs 4267 months apart.
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  29. ↑ Gene Weingarten, 'Me, in a Nutshell', Washington Post (USA), 8 March 2009, Page W32 (accessed 9 March 2009).
  30. ↑ "Cassius Dio, Roman History 60.26".
  31. ↑ Littmann, Mark; Espenak, Fred; Willcox, Ken (2008-07-17). Totality: Eclipses of the Sun. OUP Oxford. ISBN   978-0-19-157994-3.
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  33. ↑ Morrison, Jessica (2017-08-01). Eclipses. Weigl Publishers. ISBN   978-1-4896-5814-2.
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