The Sevenfold Sun Miracle was an atmospheric phenomenon witnessed in

Gdańsk Gdańsk ( , also ; ; csb, Gduńsk;Stefan Ramułt, ''Słownik języka pomorskiego, czyli kaszubskiego'', Kraków 1893, Gdańsk 2003, ISBN 83-87408-64-6. , Johann Georg Theodor Grässe, ''Orbis latinus oder Verzeichniss der lateinischen Benen ...

in 1661. It was a complex halo phenomenon, and was described by Georg Fehlau, the pastor of the St Marien church, in a sermon two weeks later, which was then published under the title ''Siebenfältiges Sonnenwunder oder sieben Nebensonnen, so in diesem 1661 Jahr den 20. Februar neuen Stils am Sonntage Sexagesima um 11 Uhr bis nach 12 am Himmel bei uns sind gesehen worden'' ("Sevenfold sun miracle or seven sun dogs which were seen in our skies on Sexagesima Sunday, 20th of February of the year 1661 from 11 o'clock until after 12 o'clock") The same event was also described by the astronomer Johan Hevelius the following year in his book ''Mercurius in Sole visus Gedani''.

The event

On 20 February 1661 a complex halo phenomenon was observed by more than 1000 people, including Fehlau and Hevelius, both astronomers, in the city of Gdańsk on the Baltic. As well as the true Sun, two mock Suns ( parhelia) and an

anthelion An anthelion (plural anthelia, from late Greek ανθηλιος, "opposite the sun") is a rare optical phenomenon of the halo family. It appears on the parhelic circle opposite to the sun as a faint white spot, not unlike a sundog, and may be c ...

were seen, with halos at 22° and 46°, and topped with an

upper tangent arc Tangent arcs are a type of halo, an atmospheric optical phenomenon, which appears above and below the observed Sun or Moon, tangent to the 22° halo. To produce these arcs, rod-shaped hexagonal ice crystals need to have their long axis alig ...

and a

circumzenithal arc The circumzenithal arc, also called the circumzenith arc (CZA), upside-down rainbow, and the Bravais arc,"Mémoire sur les halos et les phénomènes optiques qui les accompagnent", J. de l' École Royale Polytechnique 31(18), 1-270, A. Bravais, ...

, respectively. Of particular interest to modern scientists were the mention of three further mock Suns, one at the intersection of the 22° halo and the upper tangent arc, and two others at 90° to the Sun, also at the intersections of an immense but incomplete halo. The first is thought to be a particularly bright

Parry arc A Parry arc is a rare halo, an optical phenomenon which occasionally appears over a 22° halo together with an upper tangent arc. Discovery The halo was first described by Sir William Edward Parry (1790–1855) in 1820 during one of his Arctic ...

, mistakenly described as a parhelion. The other two and the associated halo, which has been labelled "Hevel's halo", have no theoretical explanation, and have not been recorded since (though one possible sighting was reported in 1909). In the absence of conclusive evidence these observations are regarded as possibly being a misidentification of the rare but not unusual 120° parhelia.Naylor p146Schaaf p46-47Vornhusen
article
at meteoros.de; retrieved 21 September 2016

The accounts

On 6 March, two weeks after the event, Fehlau preached at St Mary's church; taking the event, and the widespread interest it created, as his inspiration. His sermon was later published, and contains a full account of the phenomenon. The following year Hevelius published his book ''Mercurius in Sole visus Gedani'' ("Mercury appeared in the Sun, at Gdansk"), principally on the observation of a transit of Mercury, but containing other astronomical information, including an account of the 1661 halos.Hevelius: ''Mercurius in Sole visus Gedani'' p173-6 As the two accounts are virtually identical, and as Fehlau is known to have visited Hevelius on 3 March at his observatory to look at a comet, modern astronomers believe Fehlau and Hevelius collaborated on the text, though they generally give Hevelius (being the better-known of the two) the credit for the account.

Fehlau's account

The translation of Fehlau's account reads (''notes added for clarity''):

Notes

References

*Robert Greenler ''Rainbows, Halos and Glories'' (1980) Cambridge University Press *John Naylor
Out of the Blue; a 24 hour skywatchers guide
' (2002) Cambridge University Press *Fred Schaaf
The Starry Room; naked eye astronomy in the intimate universe
' (1988 rev. 2002) Dover Publications *Mark Vornhuse

at meteoros.de; retrieved 21 Sept 2016

External links

Fehlau's book (catalogued)
at the Herzog August Bibliothek,

Wolfenbüttel Wolfenbüttel (; nds, Wulfenbüddel) is a town in Lower Saxony, Germany, the administrative capital of Wolfenbüttel District. It is best known as the location of the internationally renowned Herzog August Library and for having the largest ...

"First report" article at meteoros.de
(in German) with Fehlau's original text
''Mercurius in Sole visus Gedani''
by

Hevelius Johannes Hevelius Some sources refer to Hevelius as Polish: * * * * * * * Some sources refer to Hevelius as German: * * * * *of the Royal Society * (in German also known as ''Hevel''; pl, Jan Heweliusz; – 28 January 1687) was a councillor ...