Dante may have known about the constellation in the 14th century, as he describes an asterism of four bright stars in the southern sky in his Divine Comedy. By 400 CE, the stars in the constellation now called Crux never rose above the horizon throughout most of Europe. However, the precession of the equinoxes gradually lowered the stars below the European horizon, and they were eventually forgotten by the inhabitants of northern latitudes. They were entirely visible as far north as Britain in the fourth millennium BC. The bright stars in Crux were known to the Ancient Greeks, where Ptolemy regarded them as part of the constellation Centaurus. Nearby to the southeast is a large dark nebula spanning 7° by 5° known as the Coalsack Nebula, portions of which are mapped in the neighbouring constellations of Centaurus and Musca. Crux also contains the bright and colourful open cluster known as the Jewel Box (NGC 4755) on its eastern border. Many of these brighter stars are members of the Scorpius–Centaurus association, a large but loose group of hot blue-white stars that appear to share common origins and motion across the southern Milky Way.Ĭrux contains four Cepheid variables, each visible to the naked eye under optimum conditions. ε Crucis (Ginan) also lies within the cross asterism. The three other stars of the cross appear clockwise and in order of lessening magnitude: β Crucis (Mimosa), γ Crucis (Gacrux), and δ Crucis (Imai). It has attained a high level of cultural significance in many Southern Hemisphere states and nations.īlue-white α Crucis (Acrux) is the most southerly member of the constellation and, at magnitude 0.8, the brightest. Even though it is the smallest of all 88 modern constellations, Crux is among the most easily distinguished as its four main stars each have an apparent visual magnitude brighter than +2.8. It lies on the southern end of the Milky Way's visible band. Visible at latitudes between + 20° and − 90°.īest visible at 21:00 (9 p.m.) during the month of May.Ĭrux ( / k r ʌ k s/) is a constellation of the southern sky that is centred on four bright stars in a cross-shaped asterism commonly known as the Southern Cross.
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