Astronomy:Solar eclipse of August 18, 1868
Script error: No such module "Solar eclipse". A total solar eclipse occurred at the Moon's ascending node of orbit on Tuesday, August 18, 1868 (also known as "The King of Siam's eclipse"),[1] with a magnitude of 1.0756. 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 6.5 days after perigee (on August 17, 1868, at 22:35 UTC), the Moon's apparent diameter was larger.[2]
The path of totality was visible from parts of modern-day Ethiopia, Eritrea, Djibouti, Yemen, India, the Andaman and Nicobar Islands, Myanmar, Thailand, Cambodia, Vietnam, Malaysia, Brunei, Indonesia, and Papua New Guinea. A partial solar eclipse was also visible for parts of East Africa, the Middle East, Central Asia, South Asia, Southeast Asia, Australia, and western Oceania.
The total solar eclipse of 18 August 1868 was accurately predicted by King Mongkut of Siam, whose calculations were acknowledged as more precise than those of contemporary French astronomers. During observations of the eclipse, Pierre Janssen in Siam and, independently, Norman Lockyer in England detected a new yellow spectral line in the Sun's chromosphere using spectroscopes, leading to the discovery of the chemical element helium.
Observations
-
Bullock sketch of the eclipse, Total Eclipses of the Sun, 1900. -
M. Stephan sketches of the eclipse, Archives des missions scientifiques et littéraires, 1868. -
Map of the forecast path of the total eclipse, Archives des missions scientifiques et littéraires, 1868.
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Several expeditions were sent to observe the eclipse.
- One of two expeditions from Germany was sent to Aden. The expedition was led by Gustav Spörer.[3]
- The second expedition was sent to the west coast of India. The expedition was led by Friedrich Tietjen.[4]
- Captain Bullock observed from the Celebes Sea, sketching the appearance of the corona,[5] while Gustav Fritsch accompanied an expedition to Aden.[6]
Discovery of helium
French astronomer Pierre Janssen observed the eclipse from Guntur in Madras State, British India. It was the first total eclipse since Gustav Kirchhoff's 1859 theory that the Fraunhofer lines in the solar spectrum correspond to the emission line of the different chemical elements present in the Sun. Correspondingly, Janssen observed the eclipse with the aid of a spectroscope. He noticed a bright yellow line (λ = 587.49 nm) in the spectra of the solar prominences that could not be due to sodium as had previously been assumed, and was subsequently able to observe the same line even without the need for an eclipse. The same result was found independently by British astronomer Norman Lockyer, and both Janssen's and Lockyer's communications were presented to the French Academy of Sciences on October 26, 1868.[7][8]
King Mongkut's calculation
King Mongkut, Rama IV of Siam, predicted and calculated the solar eclipse two years prior.[9] The calculations were correct as to the place, time, and type of the solar eclipse that would occur. His calculations were better — by about two seconds — than those of the French astronomers, who acknowledged his accuracy.[10] Mongkut invited foreign dignitaries and scientists, including Sir Harry Ord, the Governor of the Straits Settlements, and the French expedition led by Pierre Janssen[11][12] that led to the discovery of helium.[13] The event demonstrated Siam's engagement with modern science and diplomacy.[12]
Mongkut was exposed to malaria around this time, developing chills and fever. He died a month and a half after the eclipse, on 1 October 1868.[14] According to the Thai Astronomical Society and NASA, this eclipse is known as "The King of Siam's eclipse".[9][15][10][12][13][11]
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.[16]
| Event | Time (UTC) |
|---|---|
| First Penumbral External Contact | 1868 August 18 at 02:34:50.2 UTC |
| First Umbral External Contact | 1868 August 18 at 03:27:59.0 UTC |
| First Central Line | 1868 August 18 at 03:29:29.6 UTC |
| First Umbral Internal Contact | 1868 August 18 at 03:31:00.1 UTC |
| First Penumbral Internal Contact | 1868 August 18 at 04:24:13.7 UTC |
| Greatest Duration | 1868 August 18 at 05:08:35.7 UTC |
| Ecliptic Conjunction | 1868 August 18 at 05:11:42.5 UTC |
| Greatest Eclipse | 1868 August 18 at 05:12:09.6 UTC |
| Equatorial Conjunction | 1868 August 18 at 05:13:17.9 UTC |
| Last Penumbral Internal Contact | 1868 August 18 at 06:00:03.7 UTC |
| Last Umbral Internal Contact | 1868 August 18 at 06:53:18.8 UTC |
| Last Central Line | 1868 August 18 at 06:54:49.0 UTC |
| Last Umbral External Contact | 1868 August 18 at 06:56:19.2 UTC |
| Last Penumbral External Contact | 1868 August 18 at 07:49:29.4 UTC |
| Parameter | Value |
|---|---|
| Eclipse Magnitude | 1.07561 |
| Eclipse Obscuration | 1.15693 |
| Gamma | −0.04434 |
| Sun Right Ascension | 09h51m00.1s |
| Sun Declination | +13°02'06.8" |
| Sun Semi-Diameter | 15'48.4" |
| Sun Equatorial Horizontal Parallax | 08.7" |
| Moon Right Ascension | 09h50m57.4s |
| Moon Declination | +12°59'28.9" |
| Moon Semi-Diameter | 16'42.8" |
| Moon Equatorial Horizontal Parallax | 1°01'20.3" |
| ΔT | 2.2 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.
| August 3 Descending node (full moon) |
August 18 Ascending node (new moon) |
September 2 Descending node (full moon) |
|---|---|---|
| 200px | ||
| Penumbral lunar eclipse Lunar Saros 107 |
Total solar eclipse Solar Saros 133 |
Penumbral lunar eclipse Lunar Saros 145 |
Related eclipses
Eclipses in 1868
- A penumbral lunar eclipse on February 8.
- An annular solar eclipse on February 23.
- A penumbral lunar eclipse on March 8.
- A penumbral lunar eclipse on August 3.
- A total solar eclipse on August 18.
- A penumbral lunar eclipse on September 2.
Metonic
- Preceded by: Solar eclipse of October 30, 1864
- Followed by: Solar eclipse of June 6, 1872
Tzolkinex
- Preceded by: Solar eclipse of July 8, 1861
- Followed by: Solar eclipse of September 29, 1875
Half-Saros
- Preceded by: Lunar eclipse of August 13, 1859
- Followed by: Lunar eclipse of August 23, 1877
Tritos
- Preceded by: Solar eclipse of September 18, 1857
- Followed by: Solar eclipse of July 19, 1879
Solar Saros 133
- Preceded by: Solar eclipse of August 7, 1850
- Followed by: Solar eclipse of August 29, 1886
Inex
- Preceded by: Solar eclipse of September 7, 1839
- Followed by: Solar eclipse of July 29, 1897
Triad
- Preceded by: Solar eclipse of October 17, 1781
- Followed by: Solar eclipse of June 20, 1955
Solar eclipses of 1866–1870
Template:Lunar year eclipse set info The partial solar eclipses on April 15, 1866 and October 8, 1866 occur in the previous lunar year eclipse set, and the solar eclipses on June 28, 1870 (partial) and December 22, 1870 (total) occur in the next lunar year eclipse set.
| Solar eclipse series sets from 1866 to 1870 | ||||||
|---|---|---|---|---|---|---|
| Descending node | Ascending node | |||||
| Saros | Map | Gamma | Saros | Map | Gamma | |
| 108 | March 16, 1866 150px Partial |
1.4241 | 113 | |||
| 118 | March 6, 1867 150px Annular |
0.7716 | 123 | August 29, 1867 150px Total |
−0.7940 | |
| 128 | February 23, 1868 150px Annular |
0.0706 | 133 | August 18, 1868 150px Total |
−0.0443 | |
| 138 | February 11, 1869 150px Annular |
−0.6251 | 143 | August 7, 1869 150px Total |
0.6960 | |
| 148 | January 31, 1870 150px Partial |
−1.2829 | 153 | July 28, 1870 150px Partial |
1.5044 | |
Saros 133
Template:Solar Saros series 133
Metonic series
Template:Metonic eclipse set info All eclipses in this table occur at the Moon's ascending node.
| 24 eclipse events between March 25, 1819 and August 20, 1906 | ||||
|---|---|---|---|---|
| March 25–26 | January 11–12 | October 30–31 | August 18–20 | June 6–7 |
| 107 | 109 | 111 | 113 | 115 |
| 150px March 25, 1819 |
150px January 12, 1823 |
150px October 31, 1826 |
150px August 18, 1830 |
150px June 7, 1834 |
| 117 | 119 | 121 | 123 | 125 |
| 150px March 25, 1838 |
150px January 11, 1842 |
150px October 30, 1845 |
150px August 18, 1849 |
150px June 6, 1853 |
| 127 | 129 | 131 | 133 | 135 |
| 150px March 25, 1857 |
150px January 11, 1861 |
150px October 30, 1864 |
150px August 18, 1868 |
150px June 6, 1872 |
| 137 | 139 | 141 | 143 | 145 |
| 150px March 25, 1876 |
150px January 11, 1880 |
150px October 30, 1883 |
150px August 19, 1887 |
150px June 6, 1891 |
| 147 | 149 | 151 | 153 | |
| 150px March 26, 1895 |
150px January 11, 1899 |
150px October 31, 1902 |
150px August 20, 1906 | |
Tritos series
Template:Solar Tritos series 2010 July 11
Inex series
Template:Solar Inex series 2013 May 10
Notes
- ↑ "The Eclipse That Killed a King (and May Have Saved a Kingdom)". Science History Institute. https://www.sciencehistory.org/stories/magazine/the-eclipse-that-killed-a-king-and-may-have-saved-a-kingdom/.
- ↑ "Moon Distances for London, United Kingdom, England". timeanddate. https://www.timeanddate.com/astronomy/moon/distance.html?year=1868&n=136.
- ↑ Gustav Spoerer (1869). Die Reise nach Indien zur Beobachtung der totalen Sonnenfinsterniss am 18. August 1868: Vortrag gehalten in der Singakademie zu Berlin am 16. Januar 1869. Engelmann. https://archive.org/details/bub_gb_PkBSAAAAcAAJ.
- ↑ Zeitschrift. D. Reimer. 1870. pp. 608–. https://books.google.com/books?id=BTNCAQAAMAAJ&pg=PA608.
- ↑ Edward Walter Maunder, British Astronomical Association (1899). The Indian Eclipse, 1898: Report of the Expeditions Organized by the British Astronomical Association to Observe the Total Solar Eclipse of 1898 January 22. Hazell, Watson, and Viney. p. 113. https://archive.org/details/indianeclipsere00assogoog.
- ↑ Standard Encyclopaedia of Southern Africa
- ↑ Leggett, Hadley (August 18, 2009), Aug. 18, 1868: Helium Discovered During Total Solar Eclipse, wired.com, https://www.wired.com/thisdayintech/2009/08/dayintech_0818/, retrieved 2010-03-18.
- ↑ "Comptes rendus hebdomadaires des séances de l'Académie des sciences", C. R. Acad. Sci. Paris 67: 836–841, 1868, http://gallica.bnf.fr/ark:/12148/bpt6k3024c.image.r=comptes-rendus+hebdomadaires+Acad%C3%A9mie+des+Sciences.f836.langFR.
- ↑ 9.0 9.1 ๒๐๐ ปี พระบาทสมเด็จพระจอมเกล้าเจ้าอยู่หัว พระบิดาแห่งวิทยาศาสตร์ไทย. Script error: The function "in_lang" does not exist.
- ↑ 10.0 10.1 Orchiston, Wayne; Orchiston, Darunee Lingling (2021). "King Rama IV, Sir Harry Ord and the Total Solar Eclipse of 18 August 1868: Power, Politics and Astronomy". Journal of Astronomical History and Heritage 24 (2): 389–404. doi:10.3724/SP.J.1440-2807.2021.02.07. https://ui.adsabs.harvard.edu/abs/2021JAHH...24..389O/abstract.
- ↑ 11.0 11.1 "Henry Alabaster's 'Catalogue of Siamese manuscripts' (1): Royal edicts and books of laws". British Library. 19 June 2023. https://blogs.bl.uk/asian-and-african/2023/06/henry-alabasters-catalogue-of-siamese-manuscripts-1-royal-edicts-and-books-of-laws.html.
- ↑ 12.0 12.1 12.2 Aubin, David (2010). "Eclipse Politics in France and Thailand, 1868". The Heavens on Earth: Observatories and Astronomy in Nineteenth-Century Science and Culture. Duke University Press. pp. 86–117. doi:10.1515/9780822392507-006. ISBN 9780822347996. https://www.degruyterbrill.com/document/doi/10.1515/9780822392507-006/html.
- ↑ 13.0 13.1 Orchiston, Wayne (2017). "King Rama IV and French Observations of the 18 August 1868 Total Solar Eclipse from Wah-koa, Siam". in Orchiston, Wayne; Nha, Il-Seong; Strom, Richard. The Emergence of Astrophysics in Asia: Opening a New Window on the Universe. Springer. pp. 127–151. doi:10.1007/978-3-319-51173-0_9. https://link.springer.com/chapter/10.1007/978-3-319-51173-0_9.
- ↑ Montes-Bradley, Saul M.; Bradley, W.L. (10 January 2006). "Descendants of Danyell Broadley de West Morton" (964-word excerpt from Siam then, the foreign colony in Bangkok before and after Anna, Pasadena, California, 1981.). Eighth Generation. Thomas Osgood Bradley Foundation. http://www.bradleyfoundation.org/genealogies/Bingley/tobg88.htm#21153. "King Mongkut's prediction surpassed those of European scientists. "In the 19th century, King Mongkut of Siam (now Thailand), an amateur astronomer, paid the ultimate price for eclipse-chasing: his life."
- ↑ Candey, Robert. M. (28 Sep 2009). "Solar Eclipses of Historical Interest" (in en). NASA. https://eclipse.gsfc.nasa.gov/SEhistory/SEhistory.html#1868.
- ↑ "Total Solar Eclipse of 1868 Aug 18". EclipseWise.com. https://eclipsewise.com/solar/SEprime/1801-1900/SE1868Aug18Tprime.html.
References
- NASA chart graphics
- www.starwrite.org: Solar Astronomy in 1868
- Observations of the Total Solar Eclipse of August 18, 1868 by Charles G. Perrins
- Drawing of Corona
- Mabel Loomis Todd (1900). Total Eclipses of the Sun. Little, Brown. https://books.google.com/books?id=FI0-AAAAYAAJ.
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