The Saturn Nebula
Posted by Brian Ventrudo
Let’s look at one more fine object in southern Aquarius. This small but amazingly complex planetary nebula lies right next to the 4th-magnitude star nu Aquarii, so it’s not hard to find. A small telescope reveals a hint of the nebula’s complexity, and at high magnification the object appears to sprout tiny side lobes that make it look like the planet Saturn. So it’s sometimes called the Saturn Nebula…
To find the Saturn Nebula, also known as NGC 7009, look 2º northeast of the small cluster M73, which you met in the last article and 1º west of ν (nu) Aquarii.
The nebula is small but fairly bright. At low power, it looks like a slightly swollen 8th-magnitude star. At 100x, the nebula appears as a pale green glow with a 12th-magnitude central star visible in a 3-inch or larger scope. A UHC filter will make the star disappear, but it may reveal more detail including a barely perceptible inner shell.
In a 10-12 inch telescope at 200x or more, the nebula reveals far more detail, including two slender arms radiating in opposite directions from the center. This makes it resemble the planet Saturn with nearly-edge-on rings. The nebula stretches across a compact angle of 45″x25″, a little larger than the apparent size of the planet Saturn.
NGC 7009 was discovered by William Herschel in 1782 with one of his early home-built telescopes. It was named the “Saturn Nebula” by Lord Rosse in 1840. For years, Rosse got a closer look than anyone before at hundreds of deep-sky objects with his giant Leviathan of Parsonstown.
The central star of this planetary is becoming a white dwarf, an exposed core of a mid-sized star that’s run out of fuel. It will slowly radiate heat into space for the next untold billions of years.