Star Tales – Norma

One of the constellations introduced by the French astronomer Nicolas Louis de Lacaille following his mapping of the southern skies in 1751–52. It is composed of faint stars between Ara and Lupus that were not catalogued by Ptolemy. On his 1756 planisphere Lacaille called it l’Equerre et la Regle and depicted it as a draughtsman’s set-square and rule, placed next to the compasses (le Compas, now known as Circinus) and the southern triangle (Triangulum Australe), an earlier invention of Keyser and de Houtman which Lacaille visualized as a builder’s level. On the 1763 edition of the planisphere the name of the constellation was Latinized and shortened to Norma, meaning set square, although others continued to call it Norma et Regula, as did Bode on his atlas of 1801.

In his widely quoted book Star Names, Their Lore and Meaning, the historian R. H. Allen called this constellation “the Level and Square”. Allen said that the French edition of Flamsteed’s star atlas (i.e. the Atlas Céleste of Jean Fortin) showed it as Niveau, the level, but a glance at that atlas shows he is wrong. The alternative name “level” was actually applied to the southern triangle, Triangulum Australe. Allen seemingly misread the French map and transferred the name to the wrong constellation, in a reprise of the way in which star names were misapplied through misreadings of maps down the ages. Allen’s error has caused confusion ever since.

Norma, shown under the name Norma et Regula in the Uranographia of Johann Bode. “Rule and Square” is an old English pub name.

The brightest stars of Norma are of only fourth magnitude and none have names. Because of changes in the constellation’s boundaries since Lacaille’s time, Norma no longer has stars labelled Alpha or Beta. The stars that Lacaille designated Alpha and Beta Normae are now part of Scorpius where they are known as N and H Scorpii respectively. For a modern chart of this region, click here. Incidentally, Norma shares this distinction with Puppis and Vela, both of which lack stars labelled Alpha and Beta because they were once part of the much larger constellation Argo Navis; when Argo was split into three by Lacaille, the stars Alpha and Beta ended up in the third subdivision, Carina.