• Acrux Acrux is a star in Crux. ########### ############### ################### ################### ################### ################### ################### ############### ########### Type Blue-white subgiant Constellation Crux Magnitude 1.3 Spectral type B0.5IV Distance 321 light years Double star components 4.4″ apart You need naked eye Known as Bayer α¹ Cru Yale HR 4730 More information about Acrux Acrux is the brightest star of the Southern Cross and marks its foot, the end that is extended to find the south pole of the sky. A small telescope splits it into two blue stars of almost equal brightness, and there is a third further out. The name is not old and not from any language: it is the letter A, for the first star of the constellation, stuck on the front of Crux. Several southern stars were named this way in the twentieth century when navigators needed something pronounceable. Bayer lettered the stars of each constellation in his Uranometria of 1603, in order of brightness. He was working from Tycho's magnitudes by eye, and the order he recorded is often wrong. First published in 1930 by Yale astronomer Frank Schlesinger, and maintained since, the Yale Bright Star Catalogue lists every star down to magnitude 6.5. It contains 9,110 stars. where it is tonight: skymap.sh/Acrux