The Southern Cross is one of the best known patterns in the night sky, and the most familiar star pattern for us in the southern hemisphere.
Composed of five stars it forms the shape of a cross and is the most distinctive feature of the constellation Crux. It is the smallest constellation in the sky. The Southern Cross is notable for containing two bright stars, Acrux and Gacrux, the top and bottom stars which point the way to the Southern Celestial Pole.
It is one of the easiest star groups to identify in the sky and it has significance in a number of cultures in the southern latitudes.
The five stars that form it are represented on the flags of Australia, New Zealand, Papua New Guinea, Samoa, and Brazil. The Southern Crossx is also included in the national anthems of Australia and Brazil.
The Southern Cross dominates the Crux constellation and so is often confused for the constellation itself. The constellation Crux or Crucis contains many more than five stars. The stars that form the cross pattern are the brightest ones. The cross-shaped pattern can easily be seen from the southern latitudes at any time of year.
Observers in the tropical latitudes of the northern hemisphere can see it near the horizon in winter and spring, but only for a few hours every night. I once saw it around early June on the Tropic of Cancer.
The Southern Cross is located near the larger constellation Centaurus, which surrounds it on three sides. Crux constellation is also bordered by Musca, the Fly.
To find the Southern Cross, first look for the two very bright stars nearby, Alpha and Beta Centauri. Following a line from Alpha to Beta Centauri will take you near Gamma Crucis, the top star in the cross.
The Southern Cross spans only six degrees from north to south.
The Southern Cross should not be confused with the so-called False Cross, formed by four other bright stars in the vicinity. The X-shaped False Cross bears a slight resemblance to the Southern Cross and is oriented in approximately the same way, but the four stars – two belonging to the constellation Vela, the Sails, and two to Carina, the Keel – are located a bit farther to the north, and they do not point to the Southern Celestial Pole. They will, however, mark the pole’s location around the year 8600, when the pole has gradually shifted to a point just east to the intersection of the False Cross’ cross-arms.