Job’s Coffin Asterism Is Diamond in Delphinus the Dolphin Constellation

Summary: Job’s Coffin asterism is a diamond in Delphinus the Dolphin constellation, glimmering east of Aquila the Eagle constellation’s brilliant star, Altair.

Job's Coffin asterism comprises a diamond of four stars marking the head in Delphinus the Dolphin constellation; Delphinus the Dolphin illustration (upper left), east of Aquila the Eagle constellation (center) in Alexander Jamieson’s A Celestial Atlas, Plate X (1822), Public Domain, via U.S. Naval Observatory

Job’s Coffin asterism is a diamond in small Delphinus the Dolphin constellation, glimmering at mid-northern latitudes in October in the southwestern area of the night sky.

The asterism’s home constellation lies east of Aquila the Eagle constellation and south of Cygnus the Swan constellation. Altair, Aquila’s brightest star, and Deneb, Cygnus’ brightest star, form a multi-constellatory asterism, the Summer Triangle, with Vega, Lyra’s brightest star. The Summer Triangle, which is actually visible as an asterism through December, gathers together the night sky’s fifth brightest star, Vega; 12th brightest star, Altair; and 19th brightest star, Deneb.

Job’s Coffin asterism perches below the imaginary line connecting Altair with Deneb in the Summer Triangle asterism. The Summer Triangle asterism shines far more brightly than Job’s Coffin asterism’s dimmer stars. The Summer Triangle’s stars shine brilliantly as zero and first magnitude stars. Contrastingly, Job’s Coffin asterism’s stars are classed as third and fourth magnitude stars. The lower the number in apparent magnitude, the brighter the shine.

Job’s Coffin asterism’s diamond comprises four of the five brightest stars in Delphinus the Dolphin constellation. The diamond’s four stars represent the dolphin’s head.

Gamma Delphini (γ Del; γ Delphini) marks the northeasternmost point in Job’s Coffin asterism. Gamma Delphini is a binary star system, with a yellow-white dwarf as the primary component and an orange subgiant for companion. Gamma Delphini ranks as the third brightest star, both in Job’s Coffin asterism and in the asterism’s parent constellation, Delphinus the Dolphin.

Delta Delphini (δ Del) lies to the southwest of Gamma Delphini. Delta Delphini is actually a close binary star system comprising two variable stars. Delta Delphini ranks as Job’s Coffin asterism’s dimmest star and as the fifth brightest star in Delphinus the Dolphin constellation.

Alpha Delphini (α Delphini; Alpha Del; α Del) lies to the west of Gamma Delphini. Alpha Delphini is a binary star system. Alpha Delphini has five other components, which, as optical companions, appear close from Earth’s perspective but which actually have no physical association with Alpha Delphini’s pair. Alpha Delphini shines as the second brightest star in both Job’s Coffin asterism and in Delphinus the Dolphin constellation.

Beta Delphini (β Delphini; Beta Del; β Del) marks the southwesternmost point in Job’s Coffin asterism. Beta Delphini is a close binary star system. Beta Delphini has three other components which, as optical companions, have a visual, not a physical, association with Beta Delphini’s pair. Beta Delphini shines as the brightest star in Job’s Coffin asterism as well as in the asterism’s parent constellation, Delphinus the Dolphin.

Alpha Delphini and Beta Delphini are linked through their respective popular names of Sualocin and Rotanev. Known as the Palermo Catalogue of Stars, Praecipuarum Stellarum Inerrantium Positiones Mediae Ineunte Saeculo XIX is credited with the first known use of the two mysterious names. Italian astronomer and Catholic priest Giuseppe Piazzi (July 16, 1746-July 22, 1826), who discovered the dwarf planet Ceres in 1801, supervised the compiling of the catalog, which was first published in 1803, with a second edition released in 1814.

More than a century later, in 1917, British astronomer and Anglican minister Thomas William Webb (Dec. 14, 1807-May 19, 1885) solved the mystery of the names as reverse spellings of Nicolaus Venator, a Latinization of Niccolò Cacciatore (Jan. 26, 1770-Jan. 28, 1841). Cacciatore assisted in compiling the Palermo star catalogues and succeeded his mentor, Giuseppe Piazzi, as director of the Palermo Astronomical Observatory (Osservatorio Astronomico di Palermo).

Epsilon Delphini (ε Del; ε Delphini) lies southwest of Beta Delphini. The blue-white giant star does not participate in Job’s Coffin asterism but visually links as a string streaming away from the asterism’s kitelike diamond shape. Epsilon Delphini’s traditional name, Deneb Dulfim (Arabic: Al Dhanab al Dulfim, “the tail of the dolphin”), reflects its representation of the constellatory dolphin’s tail.

Epsilon Delphini’s apparent magnitude places it as the constellation’s fourth brightest star. Its rank injects it between Job’s Coffin asterism’s two dimmest stars in Delphinus the Dolphin constellation’s list of brightest stars. Epsilon Delphini places behind asterismal Gamma Delphini, as the constellation’s third brightest, and ahead of asterismal Delta Delphini, as Delphinus’ fifth brightest star.

The origin of the name of Dolphinus the Dolphin's constellation's famous asterism, Job's Coffin, is unknown.

The takeaway for Job’s Coffin asterism is that the four star diamond in Delphinus the Dolphin constellation finds easy visibility with its placement near the brilliant, large, multi-constellatory Summer Triangle asterism.

Job’s Coffin asterism and other stars in Delphinus the Dolphin constellation: International Astronomical Union and Sky & Telescope, CC BY 3.0, via International Astronomical Union (IAU)

Acknowledgment

My special thanks to talented artists and photographers/concerned organizations who make their fine images available on the internet.

Image credits:

Delphinus the Dolphin illustration in Alexander Jamieson's A Celestial Atlas, Plate X (1822): Public Domain, via U.S. Naval Observatory @ http://aa.usno.navy.mil/library/

Job’s Coffin asterism and other stars in Delphinus the Dolphin constellation: International Astronomical Union and Sky & Telescope, CC BY 3.0, via International Astronomical Union (IAU) @ https://www.iau.org/public/images/detail/del/

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