Keyhole Nebula Previously unseen details of a mysterious, complex structure
within the Carina Nebula (NGC 3372) are revealed by this image
of the “Keyhole Nebula,” obtained with NASA’s Hubble Space
Telescope. The picture is a montage assembled from four different April 1999 telescope
pointings with Hubble’s Wide Field Planetary Camera 2, which used six different color

The picture is dominated by a large, approximately circular feature, which is part of the
Keyhole Nebula, named in the 19th century by Sir John Herschel. This region, about
8000 light-years from Earth, is located adjacent to the famous explosive variable star Eta
Carinae, which lies just outside the field of view toward the upper right. The Carina
Nebula also contains several other stars that are among the hottest and most massive
known, each about 10 times as hot, and 100 times as massive, as our Sun.

The circular Keyhole structure contains both bright filaments of hot, fluorescing gas,
and dark silhouetted clouds of cold molecules and dust, all of which are in rapid, chaotic
motion. The high resolution of the Hubble images reveals the relative three-dimensional
locations of many of these features, as well as showing numerous small dark globules
that may be in the process of collapsing to form new stars.

Two striking large, sharp-edged dust clouds are located near the bottom center and
upper left edges of the image. The former is immersed within the ring and the latter is
just outside the ring. The pronounced pillars and knobs of the upper left cloud appear
to point toward a luminous, massive star located just outside the field further toward the
upper left, which may be responsible for illuminating and sculpting them by means of
its high-energy radiation and stellar wind of high-velocity ejected material. These large
dark clouds may eventually evaporate, or if there are sufficiently dense condensations
within them, give birth to small star clusters.

The Carina Nebula, with an overall diameter of more than 200 light-years, is one of the
outstanding features of the Southern-Hemisphere portion of the Milky Way. The
diameter of the Keyhole ring structure shown here is about 7 light-years.

These data were collected by the Hubble Heritage Team and Nolan R. Walborn
(STScI), Rodolfo H. Barba’ (La Plata Observatory, Argentina), and Adeline Caulet

Larger Images

  • Photos are online at
  • Higher resolution image from the SpaceRef Gallery