This constellation, tucked awkwardly between Ophiuchus and Aquila and overlapped by the tail of Serpens, was originated in 1777 by Martin Poczobut (1728–1810), director of the Royal Observatory at Vilna (now Vilnius, Lithuania). He invented it to honour his king, Stanisław August Poniatowski, who was monarch of both Poland and Lithuania. King Stanisław was a noted patron of the arts and sciences, and the bull was a feature of his family’s coat of arms.
The head of this little bull incorporated five previously ‘unformed’ stars that Ptolemy had listed in his Almagest as lying outside Ophiuchus. Four of these (the present-day 66, 67, 68, and 70 Ophiuchi), along with some fainter neighbours, form a V-shaped group between the right shoulder of Ophiuchus and the tail of Serpens. The group reminded Poczobut of the Hyades cluster that outlines the face of Taurus the bull in the zodiac, and from this mini-Hyades he formed the face of the little bull. The fifth Ptolemaic star, which we now know as 72 Ophiuchi, lay on the bull’s right horn and was the brightest star of the constellation, magnitude 3.7. The rest of the body was fleshed out by fainter stars.
Poczobut published a catalogue of 16 component stars in Cahiers des observations astronomiques faites à l’observatoire royal de Vilna en 1773 (published 1777). This list was reprinted for wider consumption by Johann Bode in his Astronomisches Jahrbuch for 1785. The constellation was first depicted in 1778 as le Taureau Royal de Poniatowski in a revised reprint of Jean Fortin’s Atlas Céleste. Bode later Latinized its name to Taurus Poniatovii on his Uranographia of 1801 (see illustration below).
Poczobut did not realize it, but his short-lived creation contained the faint red dwarf known as Barnard’s Star, which we now know to be the second-closest star to the Sun. It lay in the bull’s head, near the present-day 66 Ophiuchi. Sadly, Poniatowski’s bull did not last long in the sky before being put out to pasture and its stars are now part of Ophiuchus and Serpens Cauda.
Taurus Poniatovii, lying above the tail of Serpens, the serpent, pictured in the Uranographia of Johann Bode (1801). The face of the bull is marked by a V-shaped group of stars reminiscent of the Hyades cluster in Taurus, the zodiacal bull. This same group of stars had previously been incorporated in another figure, Tigris, which was already abandoned by Poczobut’s day.
© Ian Ridpath. All rights reserved