Star Tales – Ursa Minor

The Little Bear was said by the Greeks to have been first named by the astronomer Thales of Miletus, who lived from about 625 BC to 545 BC. The earliest reference to it seems to have been made by the poet Callimachus of the third century BC, who reported that Thales ‘measured out the little stars of the Wain by which the Phoenicians sail’. Certainly Homer, two centuries before Thales, wrote only of the Great Bear, never mentioning its smaller counterpart. However, it is not clear whether Thales actually invented the constellation or merely introduced it to the Greeks, for Thales was reputedly descended from a Phoenician family and, as Callimachus said, the Phoenicians navigated by reference to Ursa Minor rather than Ursa Major. Aratus points out that although the Little Bear is smaller and fainter than the Great Bear, it lies closer to the pole and hence provides a better guide to true north. We have the word of Eratosthenes that the Greeks also knew Ursa Minor as the Phoenician.

Ursa Minor from the Atlas Coelestis of John Flamsteed. Polaris, the north pole star, lies at the tip of its unnaturally long tail.

Aratus called the constellation Cynosura, Greek for ‘dog’s tail’. This is the origin of the English word cynosure, meaning ‘guiding star’. According to Aratus the Little Bear represents one of the two nymphs who nursed the infant Zeus in the cave of Dicte on Crete. Apollodorus tells us that the nurses’ names were Adrasteia and Ida. Ursa Minor commemorates Ida while Adrasteia, the senior of the two, is Ursa Major.

Ursa Minor has a similar ladle shape to Ursa Major, and so it is popularly termed the Little Dipper. At the end of the Little Bear’s tail (or the dipper’s handle) is the star Alpha Ursae Minoris, commonly known by the Latin name Polaris because it is currently the nearest bright star to the north celestial pole. According to the German star-name expert Paul Kunitzsch (private communication), the first known usage of the name “stella polaris” applied to this star in print was in the Alfonsine Tables published in Venice in 1492 and subsequent editions. (The Alfonsine Tables were an updated version of Ptolemy’s Almagest prepared in Toledo, Spain, around 1260 on the order of King Alfonso the Wise. The first printed edition of the Tables was in 1483; earlier editions were in manuscript form only.) The name Stella Polaris also occurs on a globe of 1493 by Johannes Stöffler and in books by Stöffler and Peter Apian in the early 16th century. At that time, Polaris was over four times farther from the celestial pole than it is at present but was clearly becoming accepted as the pole star.

Contrary to common belief, Polaris is not particularly bright. It is in fact of second magnitude, currently lying within a degree away of the exact north celestial pole, close enough to make it an excellent guide star for navigators. Polaris will reach its closest to the north celestial pole around AD 2100, when the separation will be less than half a degree.

The second star in the Little Bear’s tail, Delta Ursae Minoris, is called Yildun, a mis-spelling of the Turkish word yildiz meaning ‘star’. According to the star-name authority Paul Kunitzsch this was wrongly thought to be a Turkish name for the pole star in Renaissance times, and it has since been arbitrarily applied to the star nearest to the true pole star. According to Kunitzsch, an Arab tradition saw the arc of stars forming the handle of the Little Dipper as representing one side of the body of a fish, the other side consisting of much fainter stars including 4 and 5 Ursae Minoris and a 5th-magnitude star in Camelopardalis labelled 32 Camelopardalis on old charts.

Two stars in the bowl of the Little Dipper, Beta and Gamma Ursae Minoris, are sometimes referred to as the Guardians of the Pole. Their names are Kochab and Pherkad. Paul Kunitzsch has been unable to trace the origin of Kochab, but thinks that it may come from the Arabic word kaukab meaning ‘star’. Pherkad is from an Arabic word meaning ‘the two calves’, referring to both Beta and Gamma Ursae Minoris.

When the Chinese constellation system was established around AD 300, the position of the celestial pole lay between the stars we know as Polaris and Kochab. The name Tianhuang dadi, translated as “great Emperor of the heavens” or “high god of heaven”, is usually said to have been given by the Chinese to Polaris. However, Sun Xiaochun and Jacob Kistemaker suggest in their book The Chinese Sky During the Han that the name Tianhuang dadi actually applied not directly to Polaris but to an almost invisible star or even a blank area of sky near to it, since the ultimate deity should be mysterious and invisible. Kochab and Pherkad were part of a Chinese constellation called Beiji, the North Pole Office.