The Southern Circumpolar Constellations
The southern circumpolar constellations are the key to to starting to identify the constellations. For anyone in the southern hemisphere they are visible at any time of the year, and nearly everyone is familiar with the striking pattern of four stars that make up the constelllation of Crux (the Southern Cross), and also the two nearby bright stars Rigil Kentaurus and Hadar (α and β Centauri respectively). This pattern of stars is visible throughout the year for most observers, although for observers farther north, the stars may become difficult to see, low on the horizon in the southern spring, espcially in the months of October and November.
Crux
The distinctive shape of the constellation of Crux is usually easy to identify although some people (especially northerners unused to the southern sky) may wrongly identify the slightly larger False Cross, formed by the stars Aspidiske and Avior (ι and ε Carinae respectively) plus κ and δ Velorum. The dark patch of the Coalsack (a dark cloud of obscuring dust) is readily visible on the eastern side between Acrux and Mimosa (α and β Crucis).
A line through Gacrux (γ Crucis) and Acrux (α Crucis) points approximately in the direction of the South Celestial Pole, crossing the faint constellations of Musca and Chamaeleon. Although there is no bright star close to the South Celestial Pole (and even the constellation in which it lies, Octans, is faint), an idea of its location helps to identify the region of sky that is always visible. (The altitude of the South Celestial Pole is equal to the observer’s latitude south of the equator.) The basic triangular shape of Octans itself is best found by extending a line from Peacock
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