This is a vast and varied nebula complex, busy with clusters and other features, surrounding the intensely active Eta Carinae system. The system itself is surrounded by the billowing Homunculus Nebula while nearby the bright clouds of material are obscured by the dark Keyhole Nebula.
The region of space around the starEta Carinae is a complex and turbulent area.
Against the wide backdrop of the Eta Carinae Nebula can be seen an expanding region of
dark gas - the 'Keyhole' of the Keyhole Nebula.
The Nebula consists of a huge cloud of ionised hydrogen
surrounding the extraordinary starEta Carinae. Eta Carinae itself is a
binary system, consisting of two massivestars
in a mutual embrace, each casting off spherical shrouds of matter to form a peculiar dumb-bell shape.
It is one of the most massive and luminousstars known, and also one of the most
variable. In the mid-nineteenth century, it was one of the
brighteststars in the sky, but has now faded very considerably.
Surrounding the hourglass of Eta Carinae is an extensive cloud of ionised gas, within which
several star clusters are in the process of forming. Clouds of dark obscuring
dust swarm through the nebula, too, and the most prominent of these is the
Keyhole Nebula, a vast and rapidly expanding dark cloud
in the central parts of the main nebula.