SkyEye: Crux

The Southern Cross

Abbreviation:	Cru
Genitive:	Crucis
Origin:	[disputed]
Fully Visible:	90°S – 25°N

Crux was visible to the ancient Greeks who considered it part of the constellation of Centaurus. It was separated into a distinct constellation by European explorers to the southern hemisphere in the sixteenth century and Dutch astronomer Petrus Plancius (1552–1622) plotted it on his 1598 celestial globe. It should not be confused with the asterism, the Northern Cross, in the northern skies.

The constellation of Crux

Notable Features

Visible Named Stars
α Cru	Acrux	The unimaginatively named Acrux is a first magnitude star.
β Cru	Mimosa	The second brightest star in the constellation is also first magnitude. In the past, it has also been known as Becrux.
γ Cru	Gacrux	This star is a wide optical double with a combined magnitude of +1.6. Its name is derived in a similar way to Acrux, that is, 'ga' (gamma) + 'crux'.
δ Cru	Imai	This name was assigned to this star in the twenty-first century. It is a type of grass which grows along the Omo River in Ethiopia.
ε Cru	Ginan	The name of this star comes from the aboriginal Wardaman people of Australia.
Other Interesting Stars
HD 108147	Tupā	This seventh-magnitude star is named for the supreme deity who created the universe in Guarani culture. It is known to have at least one exoplanet which is called Tumearandu. Tupā is located just south of Acrux (α Cru).
Deep Sky Objects
C94	Jewel Box	The Jewel Box is an open star cluster visible to the naked eye. Although first described by French astronomer Nicolas-Louis de Lacaille (1713–1762), it was British astronomer Sir John Herschel (1792–1871) who gave the cluster its popular name. Binoculars or a small telescope reveals the individual stars which are a variety of colours. Its New General Catalogue number is 4755.
C98		This is another open cluster. It is also catalogued as NGC 4609.
C99	Coalsack Nebula	In contrast to the colourful Jewel Box, this is a dark nebula which obscures the light of the Milky Way behind it.