Image Credit & Copyright: NASA/JPL/Caltech/ Galaxy Evolution Explorer GALEX.
GALEX Explorer page for this ultraviolet wavelength image: http://www.galex.caltech.edu/media/glx2012-01r_img01.html
Sometime in the past, between 5,000 and 8,000 years ago, a massive star at least ten or twenty times the mass of the Sun detonated in the constellation of Cygnus the Swan. This supernova, at a distance of 1,500 light years must have been a spectacular sight and because of the relatively close proximity to us in age and distance this object is huge on our night sky. It stretches three full degrees from end to end and with the Full Moon being a half-degree, this object is six times the diameter of our Moon as we see it on the sky. Observing this object will take some black skies and some massive apertures as it’s very faint. If you’re ever at a star party and you see a nice 18” inch Dobsonian telescope, ask them to nudge it on over to the Veil Nebula for a look.
Also because of its great size, this object is regularly broken up into separate objects for observation and classification. Let’s take a look at a few of these regions.
Western Veil Nebula (NGC 6960):
This brilliant image below of the Western Veil Nebula is provided by the Digitized Sky Survey, the NOAO, 0.9 meter telescope at the Kitt Peak National Observatory and the NASA/ESA Hubble Space Telescope which details the wispy filaments along this 15 light year-long, two light year-wide region of the Cygnus Loop which is at the far right side of the top image. The bright star, likely in the foreground, is cataloged as 52 Cygnus and is unrelated to the explosion.
Eastern Veil Nebula (NGC 6992 & NGC 6995):
The Eastern Veil (left side on the top image) as shown to us here by the incredible night sky imager, J.P. Metsavainio, is another, roughly 15 light year-long region of the supernova remnant with the main difference being, that it appears to be roughly more than three light years-wide in some areas.
The final region that we’re going to detail is the area known as Pickering’s Triangle with image provided by the great astrophotographer, Bill Snyder. This region of the Cygnus Loop is also roughly 15 light years-long and 3 light years-wide at its widest point. It’s called Pickering’s Triangle because, well it slightly resembles a triangle and Charles Pickering was credited with the discovery (Though he was just the Director of the observatory). In all, there are many more regions of the Cygnus Loop that named and cataloged, these are just a few of the major ones.
NAME: Cygnus Loop, Sharpless 103, Radio Source W78.
WHAT IS IT?: Super nova remnant approximately 5,000-8,000 years old.
HOW FAR AWAY IS IT?: Roughly 1,500 light years.
HOW BIG IS IT?: 110 light years in diameter and 3 degrees on the night sky. That’s six times the diameter of the Full Moon.
DISCOVERY: William Herschel discovered the eastern Veil on September 5, 1783. He discovered the Western Veil two nights later on the 7th. Pickering’s Triangle was discovered at Harvard University in 1904 by Williamina Fleming but credit was given to the Director of the Observatory, Charles Pickering.
APPARENT MAGNITUDE: Extremely dim and diffuse.
WHERE IS IT? (General): Constellation Cygnus the Swan.
WHERE IS IT? (Exact RA/DEC J2000): Western Veil: RA: 20h 45m 38.0s / DEC +30° 42′ 30″.