NGC 7662 - Blue Snowball Nebula

NGC 7662, the Blue Snowball, is a planetary nebula located in the constellation Andromeda, 2.5° west-southwest of the star Iota Andromedae. NGC 7662 is a fairly popular planetary nebula for casual observers.

NGC 7662 is bright, large, and somewhat elongated with apparent dimming at center, and a very faint central star. A small refractor will reveal a star-like object with slight nebulosity. The annular structure is more obvious with averted vision. The faint central area is surrounded by a suddenly brighter middle ring and a faint outer ring which does not encompass the entire periphery.

A 6-inch telescope with a magnification around 100x will reveal a slightly bluish disk. Telescopes of 16" or greater aperture may reveal slight color and brightness variations in the interior. There are two lovely bluish-green rings surrounding a slightly darker center resembling the "CBS" eye. A 13th magnitude star lies beyond the east edge.

The distance to NGC 7662 is not known with any real accuracy. According to the 1951 Skalnate Pleso Catalogue, its distance is about 1,800 light years, making its actual diameter about 20,000 AU. A more recent survey of the brighter planetaries derived a distance of about 5,600 light years, increasing the actual size to nearly 50,000 AU or 0.8 light years.

The faint central star of NGC 7662 is variable, with a magnitude range of 12 to 16. It is a bluish dwarf with a continuous spectrum and a computed temperature of about 75,000K.