Sadalsuud

Sadalsuud is Beta Aquarii, and it is the brightest star of Aquarius, a rare and remarkable object: a yellow supergiant of spectral type G0 lying at roughly 540 light years, a star of the same colour as the Sun but vastly larger and thousands of times more luminous, its modest appearance in the sky entirely the effect of its great distance. Its name, from the Arabic sa'd al-su'ud, means the luck of lucks or the luckiest of the lucky, one of a series of fortunate sa'd names given to stars of this region, the House of the Fortunate.

Sadalsuud belongs to a small cluster of Aquarius and Capricornus stars carrying sa'd, fortunate, names, Sadalmelik, Sadachbia and others among them, part of what Arabic tradition called the "asterisms of good fortune" filling this stretch of the ecliptic; the cluster of favourable names across an otherwise dim and unremarkable region of sky is thought to reflect this part of the year's association with reliable seasonal rains in the pre-Islamic Arabian calendar rather than anything about the stars' appearance. Sadalsuud's great luminosity despite its modest apparent brightness is explained entirely by distance, the same effect that makes Deneb in Cygnus appear fainter than much closer, intrinsically far dimmer stars.

The name carries the delineation. The tradition reads Sadalsuud as one of the most fortunate of stars, and Robson gives it the nature of Saturn with Mercury, reading it for good fortune of a steady and lasting kind and for success in matters of the mind and of substance. It is an unusually benign entry in a catalogue heavy with menace, and its cheerful reputation rests as much on the meaning of its ancient name as on any planetary pairing. Whatever weight one gives the astrology, the star itself is a genuine rarity, a luminous, Sun-coloured supergiant, the brightest light of the Water-bearer, shining across more than five hundred light years.

At roughly five hundred and forty light years, Sadalsuud's light left the star well before the founding of most of the historical schools of astrology discussed elsewhere in this atlas, a useful reminder of how directly the fixed-star tradition looks across time as well as space: the star an ancient astrologer named is not the star as it is now but as it was many centuries before that astrologer was born. No source earlier than the modern compiling tradition supplies Sadalsuud's specific Saturn-Mercury attribution, and its benign reputation appears to rest largely on the plain sense of its own fortunate Arabic name rather than on any distinct planetary doctrine.