It may look like something from The Lord of the Rings, but this fiery
swirl is actually a planetary nebula known as ESO 456-67. Set against a
backdrop of bright stars, the rust-coloured object lies in the
constellation of Sagittarius (The Archer), in the southern sky.
Despite the name, these ethereal objects have nothing at all to do
with planets; this misnomer came about over a century ago, when the
first astronomers to observe them only had small, poor-quality
telescopes. Through these, the nebulae looked small, compact, and
planet-like — and so were labelled as such.
When a star like the Sun approaches the end of its life, it flings
material out into space. Planetary nebulae are the intricate, glowing
shells of dust and gas pushed outwards from such a star. At their
centres lie the remnants of the original stars themselves — small,
dense white dwarf stars.
In this image of ESO 456-67, it is possible to see the various
layers of material expelled by the central star. Each appears in a
different hue — red, orange, yellow, and green-tinted bands of gas are
visible, with clear patches of space at the heart of the nebula. It is
not fully understood how planetary nebulae form such a wide variety of
shapes and structures; some appear to be spherical, some elliptical,
others shoot material in waves from their polar regions, some look like
hourglasses or figures of eight, and others resemble large, messy
stellar explosions — to name but a few.
A version of this image was entered into the Hubble's Hidden Treasures image processing competition by contestant Jean-Christophe Lambry
