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84-534: Throughout its history, the BAA has encouraged observers to make scientifically valuable observations, often in collaboration with professional colleagues. Among the BAA's first presidents was Walter Maunder , discoverer of the seventeenth century dearth in sunspots now known as the Maunder Minimum which he achieved by analysing historical observations. Later, this spirit of observing the night sky scientifically

168-492: A noctilucent cloud or an upper tangent arc . However, Maunder wrote that the phenomenon moved rapidly from horizon to horizon, which would rule out a noctilucent cloud or upper tangent arc. Further, upper tangent arc cannot occur during nighttime when the observation was made. Since he made his observation during highly intense auroral activity, he assumed it was some extraordinary auroral phenomenon, though one he had never observed again before or after. He observed Mars and

252-676: A battle between the Medes and the Lydians . Both sides put down their weapons and declared peace as a result of the eclipse. 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 in Asia Minor . An eclipse recorded by Herodotus before Xerxes departed for his expedition against Greece , which

336-489: A few decades ago. The vastness of the night sky, together with the sheer number of amateur observatories, mean that BAA members are often the first to pick up new phenomena. In recent years, the Association's leading supernova hunter, Tom Boles (President 2003–5), has discovered over 150 supernovae. He now holds the world record for the greatest number of such events discovered by any individual in history. More recently

420-544: 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 cm more distant each year. Millions of years in

504-498: A global network of planetary observers through the JUPOS collaboration . The Association's longest standing publication is its journal, published six times a year and sent to all members. Once a year, the Association also publishes a handbook which comprises an almanac for the following year. Electronic bulletins are issued to give more immediate notice by email of discoveries, astronomical news and BAA meetings. The Association operates

588-511: A longer lens is needed (over 500 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. 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

672-454: A maximum of a few minutes at any location because the Moon's umbra moves eastward at over 1700 km/h (1100 mph; 470 m/s; 1500 ft/s). Totality currently can never last more than 7 min 32 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 min 2 s. The last time an eclipse longer than 7 minutes occurred

756-691: A meeting of the Birmingham Natural History and Philosophical Society it was proposed to form a Midland Branch of the BAA. Support proved to be less than had been envisioned and there are no reports of any activity after 1903. What would become the BAA Western Australia Branch started as the Western Australian Astronomical Society in 1912. When difficulties were encountered in the mid nineteen-twenties Prof. Ross highlighted

840-543: A more precise alignment between the centers of the Sun and Moon , and because the Moon's apparent size in the sky is sometimes too small to fully cover the Sun. An eclipse is a natural phenomenon . In some ancient and modern cultures, solar eclipses were attributed to supernatural causes or regarded as bad omens . Astronomers' predictions of eclipses began in China as early as the 4th century BC; eclipses hundreds of years into

924-595: 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. 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. On average, there are about 240 solar eclipses each century. Total solar eclipses are seen on Earth because of

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1008-420: 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

1092-576: A significant role in the founding of the Association was English astronomer E. Walter Maunder , with the help of his brother Frid Maunder and William H. Maw . The first meeting of the Association was held on 24 October 1890, with 60 of the initial 283 members in attendance. Initially it was decided to run the association with a provisional 48-member Council that included four women: Margaret Huggins , Elizabeth Brown , Agnes Clerke and Agnes Giberne . The society formed several observing Sections for specialised topics in astronomy. Elizabeth Brown , possibly

1176-460: A solar eclipse was taken on July 28, 1851, by Johann Julius Friedrich Berkowski , using the daguerreotype process. 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 mm for a 35 mm camera), and for the disk to fill most of the frame,

1260-501: 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. 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

1344-420: A total eclipse occurs. The Moon orbits 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, 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

1428-485: A total solar eclipse was made in France in 1706. Nine years later, English astronomer Edmund Halley accurately predicted and observed the solar eclipse of May 3, 1715 . 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 1842 , and the first photograph (or daguerreotype ) of

1512-660: A wide range of observing Sections which specialise in particular branches of astronomy, welcoming observers and astronomy enthusiasts of all abilities in a spirit of collaboration and mutual help. It also founded and supports the Campaign for Dark Skies , a UK-wide campaign against excessive light pollution . In 2022, after seventy-nine years of leasing office space from the Royal Astronomical Society , in Burlington House , Piccadilly , London

1596-439: A year, 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. Partial eclipses are virtually unnoticeable in terms of

1680-461: 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 Earth is slightly elliptical , as is Earth's orbit around the Sun. The apparent sizes of the Sun and Moon therefore vary. The magnitude of an eclipse

1764-519: Is an affiliate organisation now called Sydney City Skywatchers to better reflect its location and membership. A West of Scotland Branch was established by an inaugural meeting held on 23 November 1894, to be based in Glasgow. In 1905 authority was granted to enrol members from the whole of Scotland, but it was not until 1937 that the name was changed to "Scottish Branch". In 1954 the Branch seceded from

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1848-416: 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 regression means that the time between each passage of

1932-448: Is no warning that injury is occurring. 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

2016-698: Is now known as the Maunder Minimum . Maunder was born in 1851, in London, the youngest child of a minister of the Wesleyan Society . He attended King's College London but never graduated. He took a job in a London bank to finance his studies. In 1873 Maunder returned to the Royal Observatory , taking a position as a spectroscopic assistant. Shortly after, in 1875, he married Edith Hannah Bustin, who gave birth to six children: four sons (one of whom died in infancy) and two daughters. Following

2100-473: Is that of archaeologist Bruce Masse, who putatively links an eclipse that occurred on May 10, 2807, BC with a possible meteor impact in the Indian Ocean on the basis of several ancient flood myths that mention a total solar eclipse. Eclipses have been interpreted as omens , or portents. The ancient Greek historian Herodotus wrote that Thales of Miletus predicted an eclipse that occurred during

2184-435: 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

2268-455: 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

2352-481: 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. 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. The safest way to view

2436-474: 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. Alternatively, a partial eclipse was visible from Persia on October 2, 480 BC. Herodotus also reports a solar eclipse at Sparta during the Second Persian invasion of Greece . The date of the eclipse (August 1, 477 BC) does not match exactly the conventional dates for

2520-399: The 2023 April 20 hybrid eclipse 's totality is over a minute in duration at various points along the path of totality. Like a focal point , the width and duration of totality and annularity are near zero at the points where the changes between the two occur. Central eclipse is often used as a generic term for a total, annular, or hybrid eclipse. This is, however, not completely correct:

2604-621: The Manchester Astronomical Society . In 1891, a group of amateurs in Australia began discussing the idea of setting up branches of the BAA in their own country. What would become the New South Wales Branch was established in 1895 and would be the only one to survive for more than a brief period. This branch became the second oldest astronomy organisation in Australia and is still in existence. It

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2688-492: 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

2772-438: The darkness described at Jesus's crucifixion was a solar eclipse. This research has not yielded conclusive results, 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

2856-559: The BAA has worked increasingly with international partners. Modern communications allow astronomers in different time zones around the world to hand over the monitoring of variable stars and planetary weather systems to colleagues on other continents as the Sun comes up, resulting in a 24-hour watch on the sky. For example, the Association's Variable Star Section works closely with the American Association of Variable Star Observers , meanwhile its Jupiter Section works with

2940-792: The BAA to form the Astronomical Society of Glasgow . In 1896 an East of Scotland Branch was formed. This Branch was dissolved due to lack of support on 3 October 1902. In 1897 a second Australian Branch was formed by 13 members living in Victoria. At the London AGM of 1907 the President noted that "the Victoria Branch appears to be in a moribund condition". The Victoria Branch was re-established in 1951 (as 'The Victorian Branch'), but only lasted until 1963. In 1901 at

3024-459: The Equator, but as the Moon is moving in the same direction as Earth's rotation at about 61 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. The width of the track of a central eclipse varies according to the relative apparent diameters of the Sun and Moon. In

3108-399: 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. 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

3192-415: The Moon through the ascending node is slightly shorter than the sidereal month. This period is called the nodical or draconic month . 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 . The Moon's orbit intersects with

3276-565: The Royal Astronomical Society. Part of Maunder's job at the Observatory involved photographing and measuring sunspots, and in doing so he observed that the solar latitudes at which sunspots occur varies in a regular way over the course of the 11-year cycle. After 1891, he was assisted in his work by his wife Annie Maunder. In 1904, he published their results in the form of the "butterfly" diagram. After studying

3360-402: 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 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

3444-402: 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. 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 ,

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3528-400: 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

3612-403: 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. Since

3696-439: 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 . 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. A hybrid eclipse occurs when

3780-513: 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 sunspots , as well as eclipses. Care must be taken, however, to ensure that no one looks through

3864-580: The World. These include:- The Association held monthly meetings in London, but also established branches to cater for members who could not attend London activities and desired to meet in their own areas. The first of these was the Northwestern Branch which served members in the Northwest of England, centred on Manchester. The Branch was formed in 1892, in 1903 it seceded from the BAA to form

3948-420: The advantages of restarting within the BAA. The inaugural meeting was held on 29 March 1927. However support was still lacking and there is no recorded activity after September 1929. Edward Walter Maunder Edward Walter Maunder (12 April 1851 – 21 March 1928) was a British astronomer . His study of sunspots and the solar magnetic cycle led to his identification of the period from 1645 to 1715 that

4032-482: The apparent size of the Moon is not large enough to completely block out the Sun. Totality thus does not occur; the Sun instead appears as a very bright ring, or annulus , surrounding the dark disk of the Moon. Annular eclipses occur once every one or two years, not annually. The term derives from the Latin root word anulus , meaning "ring", rather than annus , for "year". A partial eclipse occurs about twice

4116-580: The association moved out. In October 1890, the BAA was formed to support amateur astronomers in the UK. In many ways it is a counterpart to the Royal Astronomical Society - which primarily supports professional observers - and the two organisations have long shared the same premises. The idea for this organisation was first publicly proposed by Irish astronomer William H. S. Monck in a letter published in The English Mechanic on 12 July. Playing

4200-581: The beginning of May 664 that coincided with the beginning of the plague of 664 in the British isles. 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. A 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

4284-415: 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. This narrow track is called the path of totality. An annular eclipse, like a total eclipse, occurs when the Sun and Moon are exactly in line with Earth. During an annular eclipse, however,

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4368-475: The death of Edith in 1888, in 1890 he met Annie Scott Dill Russell (later Annie Russell Maunder , 1868–1947), a mathematician and astronomer educated at Girton College in Cambridge , with whom he collaborated for the remainder of his life. She worked as a " lady computer " at the Observatory from 1890 to 1895. In 1895 Maunder and Russell married. In 1916 Annie Maunder became one of the first women accepted by

4452-439: 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. Gamma is a measure of how centrally the shadow strikes. The last (umbral yet) non-central solar eclipse

4536-457: The duration of a total solar eclipse (in order of decreasing importance): The longest eclipse that has been calculated thus far is the eclipse of July 16, 2186 (with a maximum duration of 7 minutes 29 seconds over northern Guyana). A total solar eclipse is a rare event, recurring somewhere on Earth every 18 months on average, yet is estimated to recur at any given location only every 360–410 years on average. The total eclipse lasts for only

4620-459: The eclipse circumstances will be at any given location. 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 is used in eclipse prediction to take this slowing into account. As Earth slows, ΔT increases. ΔT for dates in

4704-427: 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. 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 km/min at

4788-578: 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 seasons , 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. Eclipses can occur only when

4872-499: The end of totality, the same effects will occur in reverse order, and on the opposite side of the Moon. A dedicated group of eclipse chasers have pursued the observation of solar eclipses when they occur around Earth. A person who chases eclipses is known as an umbraphile, meaning shadow lover. Umbraphiles travel for eclipses and use various tools to help view the sun including solar viewing glasses , also known as eclipse glasses, as well as telescopes. The first known photograph of

4956-446: 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. The following factors determine

5040-434: The future may now be predicted with high accuracy. 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 chasers or umbraphiles travel to remote locations to see solar eclipses. The Sun's distance from Earth

5124-405: 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. Estimates of the time when the Moon will be unable to occlude the entire Sun when viewed from Earth range between 650 million and 1.4 billion years in the future. Looking directly at the photosphere of

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5208-412: The invasion accepted by historians. In ancient China, where solar eclipses were known as an "eating of the Sun" ( rìshí 日食 ), the earliest records of eclipses date to around 720 BC. The 4th century BC astronomer Shi Shen described the prediction of eclipses by using the relative positions of the Moon and Sun. Attempts have been made to establish the exact date of Good Friday by assuming that

5292-429: The last bright flash of sunlight. 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. During this period, the Sun is too dim to be seen through filters. The Sun's faint corona will be visible, and the chromosphere , solar prominences , coronal streamers and possibly even a solar flare may be seen. At

5376-429: The latter being favored by most recent authors on the topic. A solar eclipse of June 15, 763 BC mentioned in an Assyrian text is important for the chronology of the ancient Near East . 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. Perhaps the earliest still-unproven claim

5460-423: 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. However, depending on how much of the Sun's disk is obscured, some darkening may be noticeable. If three-quarters or more of

5544-428: The lens is covered by a properly designed solar filter. 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. 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,

5628-414: The longest total eclipse of the 20th century at 7 min 8 s occurred on June 20, 1955 , and there will be no total solar eclipses over 7 min in duration in the 21st century. It is possible to predict other eclipses using eclipse cycles . The 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,

5712-424: 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;

5796-628: The moon do not eclipse because of the death of someone from the people but they are two signs amongst the signs of God." 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 a special prayer can be made. The first recorded observation of the corona was made in Constantinople in AD 968. The first known telescopic observation of

5880-514: The most favourable circumstances, when a total eclipse occurs very close to perigee, the track can be up to 267 km (166 mi) wide and the duration of totality may be over 7 minutes. Outside of the central track, a partial eclipse is seen over a much larger area of Earth. Typically, the umbra is 100–160 km wide, while the penumbral diameter is in excess of 6400 km. Besselian elements are used to predict whether an eclipse will be partial, annular, or total (or annular/total), and what

5964-617: The name Maunder minimum . He travelled extensively for observations going to places such as the West Indies, Lapland, India, Algiers, Mauritius. His last eclipse expedition was to Labrador for the Solar eclipse of 30 August 1905 at the invitation of the Canadian government. In 1882 Maunder (and some other European astronomers) observed what he called an "auroral beam" ; as yet unexplained, it had some similarity in appearance to either

6048-649: The only woman in England at the time to own her own observatory, became Director of the Solar Section. The Association was presented with or bequeathed various astronomical instruments, but lacked the funds to build their own observatory. A total of 477 instruments were acquired during the first 117 years since the Association was founded. In addition to members making independent arrangements there have been several more or less officially organised expeditions to observe several total solar eclipses in various parts of

6132-514: The projector (telescope, pinhole, etc.) directly. 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

6216-449: 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 tilted at about 5 degrees to Earth's orbit, its shadow usually misses Earth. Solar (and lunar) eclipses therefore happen only during eclipse seasons , resulting in at least two, and up to five, solar eclipses each year, no more than two of which can be total. Total eclipses are rarer because they require

6300-420: The same way, but not as much as does the Moon's varying distance from Earth. When Earth approaches its 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 closest distance to the Sun in early January. There are three main types of solar eclipses: A total eclipse occurs on average every 18 months when

6384-449: 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 nodes ) where the Moon's orbit crosses the ecliptic. As noted above, the Moon's orbit is also 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

6468-419: 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 antumbra , the area of shadow beyond the umbra, will see an annular eclipse. The 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

6552-439: The work of Gustav Spörer , who examined old records from the different observatories archives looking for changes of the heliographic latitude of sunspots, Maunder presented a paper on Spörer's conclusions to the Royal Astronomical Society in 1890 and analyzed the results to show the presence of a prolonged sunspot minimum in the 17-18th century in a paper published in 1894. The period, recognised initially by Spörer, now bears

6636-488: Was June 30, 1973 (7 min 3 sec). 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. The next total eclipse exceeding seven minutes in duration will not occur until June 25, 2150 . The longest total solar eclipse during the 11 000 year period from 3000 BC to at least 8000 AD will occur on July 16, 2186 , when totality will last 7 min 29 s. For comparison,

6720-422: Was on April 29, 2014 . This was an annular eclipse. The next non-central total solar eclipse will be on April 9, 2043 . The visual phases observed during a total eclipse are called: 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

6804-612: Was a driving force in the foundation of the British Astronomical Association . Although he had been fellow of the Royal Astronomical Society since 1875, Maunder wanted an association of astronomers open to every person interested in astronomy, from every class of society, and especially open for women. Maunder was the first editor of the Journal of the BAA , an office later taken by his wife Annie Maunder . He

6888-457: Was a sceptic of the notion of Martian canals . He conducted visual experiments using marked circular disks which led him to conclude, correctly, that the viewing of canals arose as an optical illusion . Also he was convinced that there cannot be life "as in our world" on Mars, as there are no temperature-equating winds and too low mean temperatures. Craters on Mars and the Moon were named in his and his wife Annie 's honour. In 1890, Maunder

6972-766: Was also director of its Mars Section 1892–1893, the Star Colour Section 1900–1901, President 1894-1896 and finally Solar Section director 1910–1925. His older brother, Thomas Frid Maunder (1841–1935), was a co-founder and secretary of the Association for 38 years. In 2022 English Heritage announced that Annie and Walter Maunder would be commemorated with a blue plaque at their former home in Brockley , London, later that year. The Maunders wrote The Heavens and their Story while they were living in Brockley. Solar eclipse A solar eclipse occurs when

7056-469: Was championed by George Alcock , who discovered five comets and five novae using nothing more than a pair of binoculars. The BAA continues to contribute to the science of astronomy, even despite modern competition from space-based telescopes and highly automated professional observatories. Modern digital sensors, coupled with techniques such as lucky imaging , mean that even modest amateur equipment can rival what professional observatories could have achieved

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