Orion’s Shield Asterism in Orion the Hunter Constellation Has Eight Stars

Summary: Orion’s Shield asterism in Orion the Hunter constellation, one of nighttime’s most conspicuous and easily recognizable starry groups, has eight stars.

Orion the Hunter with his shield; 15th century depiction, Poeticon Astronomicon by Hyginus (Venezia: Erhard Ratdolt, 1482): Public Domain, via Internet Archive

Orion’s Shield asterism in Orion the Hunter constellation, one of the night sky’s most noticeable and most easily recognizable imaginary groupings of stars, has eight stars.

Orion the Hunter constellation occupies a prominent position on the celestial equator, the imaginary great circle projected outward into space in the same plane as Earth’s equator. Orion is easily seen worldwide between the latitudes of 85 degrees north and 75 degrees south. Best visibility of the conspicuous, readily familiar constellation in nighttime skies happens from November through February.

Orion’s namesake appears in Greek mythology as a giant huntsman. His hunting dogs, depicted in Canis Major (“Greater Dog”) and Canis Minor (“Lesser Dog”) constellations, faithfully follow him across the sky. Lepus the Hare constellation resides as a typical hunting symbol immediately south of Orion. Another constellatory hunting symbol, Taurus the Bull constellation, dominates Orion’s northwestern border.

As a hunter, Orion is depicted with occupational symbols. He bears a club, held in an upraised arm; wears a sword, suspended from the constellation’s famous belt asterism; and grasps a shield, made of lion’s skin, in his other, outstretched arm.

Sometimes Orion’s Shield asterism is illustrated as a felled lion. The Leiden Aratea depicts Orion with a lion skin draped over his outstretched arm. The Leiden Aratea is an illuminated astronomical treatise created in the ninth century in the area of the medieval kingdom of Lotharingia, now northeastern France’s cultural and historical region of Lorraine. The Leiden Aratea illustrates an ancient Roman work authored by early Roman Empire General Germanicus (May 24 BCE-Oct. 10, 19 CE) as a Latin translation of Phaenomena, a poem about the constellations by Greek poet Aratus (ca. 315/310-240 BCE).

Depictions of Orion’s constellation variously present back or front views of the great hunter. A Celestial Atlas, published in 1822 by Scottish rhetorician Alexander Jamieson (1782-1850), depicts a front view, with Orion’s face turned to the left, over his left shoulder, marked by bluish-white giant star Bellatrix, and with a lion’s skin over his upraised left arm.

The International Astronomical Union, an international association founded in 1919 with the establishment of “unambiguous astronomical nomenclature” as a key mission, identifies eight stars in Orion’s Shield asterism. Blue supergiant star 11 Orionis (11 Ori) defines the asterism’s northern extent. Also Orion’s Shield’s easternmost star, 11 Orionis ranks as the asterism’s dimmest star.

Red clump giant Omicron² Orionis (o² Ori) lies southwest of 11 Orionis. Omicron² Orionis is the fourth brightest star in Orion’s Shield asterism.

Located south of the red clump giant, Pi-1 Orionis (Pi¹ Orionis; π¹ Ori; π¹ Orionis) announces the loose cluster of six Pi Orionis stars that arcingly shape around nine degrees of the more than 14 degrees of sky occupied by Orion’s Shield asterism. Pi-1 is the asterism’s seventh brightest star.

Pi-2 Orionis (Pi² Orionis; π² Ori; π² Orionis) juts southwest of Pi-1. The blue main sequence dwarf is the fifth brightest star in Orion’s Shield asterism.

Next, Pi-3 Orionis (Pi³ Orionis; π³ Ori; π³ Orionis) claims the westernmost position in Orion’s Shield. Yellowish-white dwarf Pi-3 Orionis claims status as the asterism’s brightest star. Pi-3 aligns with Bellatrix (Latin: “female warrior”) in Orion’s shoulder.

Blue giant Pi-4 Orionis (Pi⁴ Orionis; π⁴ Ori; π⁴ Orionis) perches slightly southeast of Pi-3. Pi-4 shines as the asterism’s second brightest star.

At least three degrees gape between Pi-4 and its southeastern neighbor, Pi-5 Orionis (Pi⁵ Orionis; π⁵ Ori; π⁵ Orionis). The blue-white giant is actually a binary star system, companioned by a hydrogen-fusing dwarf. Pi-5 shines as the third brightest star in Orion’s Shield asterism.

Orange red giant Pi-6 Orionis (Pi⁶ Orionis; π⁶ Ori; π⁶ Orionis) marks the asterism’s southern extent. Pi-6 is the asterism’s sixth brightest star.

The takeaway for Orion’s Shield asterism in Orion the Hunter constellation is that eight stars arcing westward from bluish-white giant Bellatrix shield the great hunter from danger as he entertains worldwide Earthly observers with elegant conspicuousness from November through February.

Orion’s Shield asterism and other stars in Orion the Hunter constellation: International Astronomical Union/Sky & Telescope, CC BY 4.0 International, 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:

Orion the Hunter with his shield; 15th century depiction, Poeticon Astronomicon by Hyginus (Venezia: Erhard Ratdolt, 1482): Public Domain, via Internet Archive @ https://archive.org/stream/OEXV540_P3#page/n86/mode/1up

Orion’s shield asterism and other stars in Orion the Hunter constellation: International Astronomical Union/Sky & Telescope, CC BY 4.0 International, via International Astronomical Union (IAU) @ http://www.iau.org/public/themes/constellations/

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