Scorpius

Stars

Scorpius contains many bright stars, including Antares (α Sco), "rival of Mars," so named because of its distinct reddish hue; β¹ Sco (Graffias or Acrab), a triple star; δ Sco (Dschubba, "the forehead"); θ Sco (Sargas, of sumerian origin^[2]); ν Sco (Jabbah); ξ Sco; π Sco (Fang); σ Sco (Alniyat); and τ Sco (Paikauhale).

Marking the tip of the scorpion's curved tail are λ Sco (Shaula) and υ Sco (Lesath), whose names both mean "sting." Given their proximity to one another, λ Sco and υ Sco are sometimes referred to as the Cat's Eyes.^[3]

The constellation's bright stars form a pattern like a longshoreman's hook. Most of them are massive members of the nearest OB association: Scorpius–Centaurus.^[4]

The star δ Sco, after having been a stable 2.3 magnitude star, flared in July 2000 to 1.9 in a matter of weeks. It has since become a variable star fluctuating between 2.0 and 1.6.^[5] This means that at its brightest it is the second brightest star in Scorpius.

U Scorpii is the fastest known nova, with a period of about 10 years.^[6]

AH Scorpii is a red supergiant star and one of the largest known stars, being 1,400 times larger than the Sun. It is also a luminous star, 340,000 times brighter than the Sun,^[7] altought is too faint to be seen to the naked eye, with a brightness varying from 6.5 to 9.6.^[8]

The close pair of stars ω¹ Scorpii and ω² Scorpii are an optical double, which can be resolved by the unaided eye. One is a yellow giant,^[9] while the other is a blue B-type star in the Scorpius-Centaurus Association.^[10]

The star once designated γ Sco (despite being well within the boundaries of Libra) is today known as σ Lib. Moreover, the entire constellation of Libra was considered to be claws of Scorpius (Chelae Scorpionis) in Ancient Greek times, with a set of scales held aloft by Astraea (represented by adjacent Virgo) being formed from these westernmost stars during later Greek times. The division into Libra was formalised during Roman times.^{[citation needed]}

Deep-sky objects

Due to its location straddling the Milky Way, this constellation contains many deep-sky objects such as the open clusters Messier 6 (the Butterfly Cluster) and Messier 7 (the Ptolemy Cluster), NGC 6231 (by ζ² Sco), and the globular clusters Messier 4 and Messier 80.

Messier 80 (NGC 6093) is a globular cluster of magnitude 7.3, 33,000 light-years from Earth. It is a compact Shapley class II cluster; the classification indicates that it is highly concentrated and dense at its nucleus. M80 was discovered in 1781 by Charles Messier. It was the site of a rare discovery in 1860 when Arthur von Auwers discovered the nova T Scorpii.^[11]

NGC 6302, also called the Bug Nebula, is a bipolar planetary nebula. NGC 6334, also known as the Cat's Paw Nebula, is an emission nebula and star-forming region.

Origins

The Babylonians called this constellation MUL.GIR.TAB - the 'Scorpion'; the signs can be literally read as 'the (creature with) a burning sting'.^[14]

In some old descriptions the constellation of Libra is treated as the Scorpion's claws. Libra was known as the Claws of the Scorpion in Babylonian (zibānītu (compare Arabic zubānā)) and in Greek (χηλαι).^[15]

Astrology

The Western astrological sign Scorpio differs from the astronomical constellation. Astronomically, the sun is in Scorpius for just six days, from November 23 to November 28. Much of the difference is due to the constellation Ophiuchus, which is used by few astrologers. Scorpius corresponds to the Hindu nakshatras Anuradha, Jyeshtha, and Mula.^{[citation needed]}