Rigel

Rigel is Beta Orionis, a blue supergiant of spectral type B8 Ia, apparent magnitude 0.13, at roughly 860 light years.

It is one of the most intrinsically luminous stars visible to the naked eye, of the order of a hundred thousand times the Sun's output. Its apparent brightness, only moderately impressive, is entirely a function of distance: Rigel is about a hundred times further away than Sirius and appears fainter, which is a useful corrective to the assumption that bright stars are near ones. It is a young, massive star and it will end as a supernova.

Rigel is a multiple system, with a companion resolvable in a small telescope which is itself a close binary. The primary is slightly variable.

It is also, in most conditions, brighter than Betelgeuse, despite carrying the Beta designation while Betelgeuse carries the Alpha. Bayer's letters were assigned by brightness only loosely and often followed position within the constellation figure; Betelgeuse's variability, which can carry it above Rigel at maximum, may have contributed to the ordering. The Alpha designation is not a claim about brightness and should not be read as one.

The name is from Arabic, rijl, the foot, the star marks Orion's left foot as seen by us. Rigel illuminates several nearby nebulae, including the Witch Head Nebula, by reflection.

Its colour is a visible contrast with Betelgeuse. The two stand at opposite corners of Orion, one blue-white and one orange-red, and the pair is the standard naked-eye demonstration that stars differ in temperature.

Rigel belongs to the loose association of hot young stars across the Orion region, formed from the same complex of gas within roughly the last ten million years. Because those stars are massive and short-lived, Orion will become unrecognisable long before most fainter constellations change appreciably.

Sources AstronomyAndrew Fraknoi, David Morrison, and Sidney C. Wolff (OpenStax) with Almagest (Mathematike Syntaxis)Claudius Ptolemy

Ptolemy gives Rigel the nature of Jupiter and Saturn, and the resulting reading is the most benefic in the Orion group: honour, riches, lasting fame, technical and inventive ability, and success won through effort.

The Jupiter half carries almost all of it. The Saturn half contributes caution, delay, and the standing risk of a fall from position, which is the qualification the tradition attaches. The combination of Jupiter and Saturn is a recognisable type in this material, elevation that is slow, earned and precarious rather than conferred, and it appears again with Canopus and, on Ptolemy's reading, with Algol, though the balance in Algol's case is entirely different.

The specific delineation of Rigel as favouring technical and inventive ability and engineering is worth flagging as late. It does not come from Ptolemy, who gives two planet names and nothing more, and it is not obviously derivable from Jupiter and Saturn without a good deal of interpretation. It appears in this form in Robson in 1923 and in the nineteenth-century sources he drew on, in a period when technical and engineering careers were a live category in a way they had not previously been. Fixed-star delineations acquire the professions of their compilers' centuries, and this is a clear instance.

Rigel is not among Agrippa's Behenian fifteen.

Orion as a constellation figure is among the oldest identifiable, appearing in Mesopotamian tradition as the Heavenly Shepherd and being referenced in the Book of Job and in Homer. The individual stars' astrological characters are Hellenistic and later; the figure is much older than the attributions.