Gacrux

Gacrux (Gamma Crucis) is the third brightest star in das Kreuz des Südens at magnitude 1.63 and the nearest red giant to die Sonne clearly mit bloßem Auge sichtbar, at about 88 Lichtjahre. It is a red giant of Spektraltyp M3.5III, about 84 times the diameter of die Sonne 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 das Kreuz des Südens. 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 März through Juli from südlichen Breiten.

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 Präzession, das Kreuz des Südens was visible from Mediterranean latitudes in ancient times — the Greeks likely knew it, and it may be referenced in Ptolemy's catalog as stars im Sternbild Zentaur.