The Helix is distinguished by its proximity to Earth, about 700 light years, and its consequent very large apparent size.
#Helix nebula full
The star is essentially ejecting its outer atmosphere and exposing its blazing hot core to full view. Like all planetary nebulae, the Helix is a region of rarefied gas thrown off by a dying star of moderate mass. Some refer to the Helix as the “Eye of God”. In images, like the excellent collaboration above led by Warren Keller at, the nebula looks like an expansive eye in deep sky. One of the closest and apparently largest of all planetary nebulae, the Helix is one of the few sights that’s easier to see in a small telescope than in a large one. The showpiece of the constellation Aquarius is the grand and elusive Helix Nebula, NGC 7293. Additional credit: Piermario Gualdoni and Alessandro Cipolat Bares. Image credit: Warren Keller at Billionsand. It's a popular object on observing lists.NGC 7293, the Helix Nebula, is a planetary nebula in the constellation Aquarius. When imaged or photographed it looks spectacular with colourful twists, coils, knots and rings of gas visible. However, it's a much more elusive object due to its low surface brightness. It's marginally brighter than M27, the Dumbbell Nebula. The Helix Nebula is located 695 light-years from Earth and has an actual radius of about 3 light-years. The central star of the Helix Nebula shines at magnitude +13.4, and therefore only easily seen in large amateur reflectors. However, it's an illusive object that can be rendered invisible even in medium size amateur telescopes with just a small amount of light pollution. A nebula filter of the UHC (Ultra High Contrast) or OIII (Oxygen III) variety, especially when combined with averted vision, helps to bring out subtle details. Through a 200mm (8-inch) reflector it appears slightly oval with two thick arcs, gaps and brightness variations across the structure. A 100mm (4-inch) telescope reveals finer structural details. When viewed through a pair of 10x50 binoculars, the Helix appears as a faint featureless oval shaped disk.
It was German astronomer Karl Ludwig Harding who eventually discovered the nebula, sometime before 1824. Charles Messier failed to spot it and the two great astronomers, Sir William and Sir John Herschel, also failed to notice it during their sky searches. The main nebula covers 18 arc minutes with the much fainter outer halo spanning some 28 arc minutes - close to the apparent diameter of the full Moon.
But that's the key, dark skies are required due to its large surface area resulting in low surface brightness. Based on this information it would seem an easy target, and is indeed visible with binoculars from a dark site.
#Helix nebula pdf
At magnitude +5.2, this star is faintly visible to the naked eye under dark skies and acts as a good marker.įinder Chart for NGC 7293 - pdf format (credit:- freestarcharts)Īt magnitude +7.3, the Helix Nebula is the brightest planetary nebula in the sky. Just over a degree east of the Helix is υ Aqr. +1.2), the brightest star in the constellation Piscis Austrinus, and ι Aqr (mag. This nebula lies roughly halfway along an imaginary line connecting Fomalhaut (α PsA - mag. It contains a double ring structure, not unlike two coils of a spring, hence the popular name the Helix Nebula.Īlthough the area of sky surrounding the Helix Nebula is devoid of bright stars, it can be easily located by star-hoping. Also known as Caldwell 63, it's one of the nearest objects of its type and a beautiful example of a remnant of a dying star. NGC 7293 is a large and well-known planetary nebula located in the faint zodiac constellation of Aquarius.