A total solar eclipse occurred at the Moon's ascending node of orbit on Monday, July 28, 1851, with a magnitude of 1.0577. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A total solar eclipse occurs when the Moon's apparent diameter is larger than the Sun's, blocking all direct sunlight, turning day into darkness. Totality occurs in a narrow path across Earth's surface, with the partial solar eclipse visible over a surrounding region thousands of kilometres wide. Occurring about 1.5 days before perigee (on July 30, 1851, at 2:30 UTC), the Moon's apparent diameter was larger.

The path of totality was visible from parts of modern-day Canada, Greenland, Iceland, Norway, Sweden, Denmark, Poland, Russia, southwestern Lithuania, Belarus, Ukraine, Moldova, Georgia, Armenia, and Azerbaijan. A partial solar eclipse was also visible for parts of North America, Europe, North Africa, Russia, the Middle East, and Central Asia.

This was the earliest scientifically useful photograph of a total solar eclipse, made by Julius Berkowski at the Royal Observatory in Königsberg, Prussia. It was the first occasion that an accurate photographic image of a solar eclipse was recorded.

Background A solar eclipse occurs when the Moon passes between the Earth and the Sun, casting a shadow on Earth that temporarily obscures part or all of the Sun's disc. Eclipses can occur only when all three bodies are properly aligned. Partial eclipses, in which only a portion of the Sun's surface is obscured, are relatively common due to the width of the Moon's outer shadow, or penumbra, which may be several hundred miles wide. Total eclipses occur when the Moon's inner shadow, or umbra, reaches the surface of the Earth, completely obscuring the Sun over a much narrower portion of the ground. If the Moon is too far away at the time of an eclipse, its umbra may not reach the Earth's surface, and only a partial eclipse will be visible.

Before the advent of modern science, solar eclipses were often viewed with superstitious dread. However, eclipses are also of interest to science due to the various phenomena that can be observed when they occur. The Sun's outer atmosphere, or corona, is normally invisible due to the brightness of the solar disc, but becomes visible from Earth during a total eclipse. Until the twentieth century, solar eclipses provided the only opportunity for scientists to observe and study the Sun's corona. With the development of photography during the first half of the nineteenth century, it became theoretically possible to record a still image of the Sun during a total eclipse. A variety of processes were used for early photographs, of which the most successful was the daguerreotype.

Observations Photographing a rare event such as a total eclipse posed unique challenges for early photography, including the extreme contrast between the corona and the dark shadow of the Moon, as well as the unusual angle to which photographic equipment had to be oriented. Prior to the eclipse of July 28, 1851, no properly exposed photograph of the solar corona had yet been produced. For this occasion, the Royal Prussian Observatory at Königsberg (now Kaliningrad, Russia) commissioned one of the city's most skilled daguerreotypists, Johann Julius Friedrich Berkowski, to record a still image of the event. The observers attached a small six-centimeter refracting telescope to a 15.8 centimeter Fraunhofer heliometer, and Berkowski made an eighty-four second exposure shortly after the beginning of totality.

Among the other observers were British astronomers Robert Grant and William Swan, and Austrian astronomer Karl Ludwig von Littrow. They deduced that prominences were part of the Sun, because the Moon was seen to cover and uncover them as it moved in front of the Sun.

Eclipse details Shown below are two tables displaying details about this particular solar eclipse. The first table outlines times at which the Moon's penumbra or umbra attains the specific parameter, and the second table describes various other parameters pertaining to this eclipse.

+July 28, 1851 Solar Eclipse Times Event Time (UTC) First Penumbral External Contact 1851 July 28 at 12:15:06.1 UTC First Umbral External Contact 1851 July 28 at 13:24:53.6 UTC First Central Line 1851 July 28 at 13:26:48.7 UTC First Umbral Internal Contact 1851 July 28 at 13:28:45.8 UTC Equatorial Conjunction 1851 July 28 at 14:21:59.0 UTC Greatest Eclipse 1851 July 28 at 14:33:41.9 UTC Greatest Duration 1851 July 28 at 14:33:48.3 UTC Ecliptic Conjunction 1851 July 28 at 14:41:27.8 UTC Last Umbral Internal Contact 1851 July 28 at 15:38:44.7 UTC Last Central Line 1851 July 28 at 15:40:43.2 UTC Last Umbral External Contact 1851 July 28 at 15:42:39.8 UTC Last Penumbral External Contact 1851 July 28 at 16:52:19.9 UTC

+July 28, 1851 Solar Eclipse Parameters Parameter Value Eclipse Magnitude 1.05765 Eclipse Obscuration 1.11863 Gamma 0.76436 Sun Right Ascension 08h28m49.7s Sun Declination +19°03'55.7" Sun Semi-Diameter 15'45.2" Sun Equatorial Horizontal Parallax 08.7" Moon Right Ascension 08h29m18.2s Moon Declination +19°49'34.3" Moon Semi-Diameter 16'29.2" Moon Equatorial Horizontal Parallax 1°00'30.3" ΔT 7.1 s

Eclipse season

This eclipse is part of an eclipse season, a period, roughly every six months, when eclipses occur. Only two (or occasionally three) eclipse seasons occur each year, and each season lasts about 35 days and repeats just short of six months (173 days) later; thus two full eclipse seasons always occur each year. Either two or three eclipses happen each eclipse season. In the sequence below, each eclipse is separated by a fortnight.

+ Eclipse season of July 1851 July 13Descending node (full moon) July 28Ascending node (new moon) Partial lunar eclipseLunar Saros 117 Total solar eclipseSolar Saros 143

Related eclipses Eclipses in 1851 A partial lunar eclipse on January 17. An annular solar eclipse on February 1. A partial lunar eclipse on July 13. A total solar eclipse on July 28.

Metonic Preceded by: Solar eclipse of October 9, 1847 Followed by: Solar eclipse of May 16, 1855

Tzolkinex Preceded by: Solar eclipse of June 16, 1844 Followed by: Solar eclipse of September 7, 1858

Half-Saros Preceded by: Lunar eclipse of July 22, 1842 Followed by: Lunar eclipse of August 1, 1860

Tritos Preceded by: Solar eclipse of August 27, 1840 Followed by: Solar eclipse of June 27, 1862

Solar Saros 143 Preceded by: Solar eclipse of July 17, 1833 Followed by: Solar eclipse of August 7, 1869

Inex Preceded by: Solar eclipse of August 16, 1822 Followed by: Solar eclipse of July 7, 1880

Triad Preceded by: Solar eclipse of September 25, 1764 Followed by: Solar eclipse of May 29, 1938

Solar eclipses of 1848–1852

The partial solar eclipses on April 3, 1848 and September 27, 1848 occur in the previous lunar year eclipse set, and the solar eclipses on June 17, 1852 (partial) and December 11, 1852 (total) occur in the next lunar year eclipse set.

Solar eclipse series sets from 1848 to 1852 Descending node  Ascending node Saros Map Gamma Saros Map Gamma 108 March 5, 1848Partial 1.3950 113 August 28, 1848Partial −1.5475 118 February 23, 1849Annular 0.7475 123 August 18, 1849Total −0.7343 128 February 12, 1850Annular 0.0503 133 August 7, 1850Total 0.0215 138 February 1, 1851Annular −0.6413 143 July 28, 1851Total 0.7644 148 January 21, 1852Partial −1.2948

Saros 143

Metonic series All eclipses in this table occur at the Moon's descending node.

24 eclipse events between March 4, 1802 and July 28, 1870March 4December 20–21October 8–9July 27–28May 15–16117119121123125March 4, 1802December 21, 1805October 9, 1809July 27, 1813May 16, 1817127129131133135March 4, 1821December 20, 1824October 9, 1828July 27, 1832May 15, 1836137139141143145March 4, 1840December 21, 1843October 9, 1847July 28, 1851May 16, 1855147149151153March 4, 1859December 21, 1862October 8, 1866July 28, 1870

Tritos series

Inex series

References

External links

NASA chart graphics Googlemap NASA Besselian elements

FIRST SUN PHOTO On the Berkowski Daguerreotype (Konigsberg, 1851 July 28): The First Correctly Exposed Eclipse Photograph of the Solar Corona From eclipse drawings to the coronagraph and spectroscopy History of Astrophotography Timeline Sketch of Solar Corona 1851 July 28 Solar eclipse of July 28, 1851 in Russia