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The Veil Nebula
The wreckage of a star that exploded, still spreading across the sky thousands of years later.
Seeing it from the UK
It sits in Cygnus, which passes almost overhead on summer and autumn evenings from the UK, so the target is easy to get at. Seeing it is another matter. Your eyes will not show it, and neither will ordinary binoculars from a town. Through a telescope with a nebula filter from a dark site it appears as a faint grey thread, with no colour, and even then people often walk past it without realising what they are looking at. Everything in the photograph above came from stacking, not from a better view. Late June to November is the season, and the darker your sky the more of the loop you get.
A star far larger than the Sun ran out of fuel and blew itself apart, somewhere between ten and twenty thousand years ago. What is left is this: a shell of gas still travelling outwards at a few hundred kilometres a second, glowing because the shock front is slamming into the thin gas that already sat between the stars.
The picture shows the western edge of it, catalogued as NGC 6960. The whole shell is far bigger than one frame, about three degrees across, which is six full moons side by side. Astronomers call the complete thing the Cygnus Loop, and the Veil is the part of it bright enough to photograph.
The colours are two different gases. Red is hydrogen and blue is oxygen, and they sit in separate ropes rather than mixed together because they light up at different distances behind the shock front. That separation is the reason a duo band filter suits this object so well, and it is why the structure looks braided rather than like a smear of cloud.
The bright star sitting on the filament is not part of the nebula at all. It is 52 Cygni, much closer to us, lined up by chance. The exploded star itself left nothing bright enough to pick out here.
The numbers
- Also called
- NGC 6960, and the Witch’s Broom
- Part of
- The Cygnus Loop, the whole supernova shell
- Constellation
- Cygnus, the swan
- Distance
- About 2,400 light years
- Exploded
- Roughly 10,000 to 20,000 years ago
- Size in the sky
- The full loop is about 3 degrees, six full moons across
- Bright star in the picture
- 52 Cygni, in front of it and unrelated
- Best months from the UK
- June to November
To find out whether it is up tonight, and when it gets properly dark where you are, see Sky Tonight.