Gacrux — Star in Crux

Gacrux (Gamma Crucis) is the third brightest star in the Southern Cross at magnitude 1.63 and the nearest red giant to the Sun clearly visible to the naked eye, at about 88 light-years. It is a red giant of spectral type M3.5III, about 84 times the diameter of the Sun and roughly 1,500 times more luminous. Its deep red color contrasts dramatically with the blue-white stars that make up the rest of the Cross.

Gacrux marks the top (northern) point of the Southern Cross. Its conspicuous red-orange color stands out sharply against the blue-white Acrux and Becrux — this color contrast is one of the finest in the southern sky. With Alpha Centauri and Beta Centauri as pointers, the Cross is easy to locate. Gacrux is visible from latitudes south of about 35°N. Best observed from March through July from southern latitudes.

The name Gacrux is a modern contraction of 'Gamma Crucis,' similar to how Acrux was formed. The star has been used for southern navigation for centuries. Because of precession, the Southern Cross was visible from Mediterranean latitudes in ancient times — the Greeks likely knew it, and it may be referenced in Ptolemy's catalog as stars in Centaurus.