Crux

Crux (the cross), commonly known as the Southern Cross, is the smallest of the 88 modern constellations, but also one of the most famous.

Notable features

Its five brightest stars (Alpha, Beta, Gamma, Delta and Epsilon Crucis) appear on the flags of Australia, Brazil, New Zealand, Papua New Guinea and Samoa, except that the New Zealand flag omits Epsilon.

With the the lack of a significant pole star in the southern sky (σ Octantis is closest to the pole, but is so faint as to be useless for the purpose), two of the stars of Crux (Alpha and Gamma, Acrux and Gacrux[?] respectively) are commonly used to mark south. Following the line defined by the two stars for approximately four times the distance between them leads to a point close to the south celestial pole.

Notable deep sky objects

The Coalsack[?] is the most prominent dark nebula in the skies, well visible to the naked eye as big dark patch in the southern Milky Way.

History

Crux was formerly part of Centaurus, and was first introduced as a separate constellation by A. Royer in 1679. Due to precession of the equinox, Crux and Centaurus were visible from the Mediterranean area in Antiquity[?], so their stars had to be known by Greeks astronomer.