This new moon weekend, let's observe just one class of object. These galactic targets are our very close neighbors in the Milky Way galaxy. Planetary nebulae are what made the Hubble Space Telescope famous in the public eye. They are photographic glamour targets, without question! But inside that photogenic beauty lies the death throes of their creators: stars at the ends of their life cycle.
As the central star in a planetary nebula burns through its fuel (losing mass and heat pressure), the star gravitationally collapses upon itself. This in turn "reheats" the star, and the heat pressure pushes its outer atmosphere away - actually casting it off into space. That creates a bubble which expands away from the star, and having lost some of its mass, the star repeats the collapse-reheat process, until it is finally out of fuel (our Sun's ultimate fate).
We benefit with views of these beautiful objects through our modest size telescopes. Here are five that are diverse in appearance, and are off the usual beaten (Messier) path. Apply some magnification to these when you find them, and enjoy their differences, and intricacies. At the end of each description is a minimum size instrument for which I've found an observing report for the object.
Click the images to see the full sized image. Ready? Let's get hopping!
NGC 40 in Cepheus is bright at mag 10.7, yet takes a bit of effort in suburban skies. Starhop to it using Navi (Gamma) in Cassiopeia, then moving about 2/3rds the distance to Errai (Gamma) in Cepheus. That puts you in the right area. The disc should be visible with a bright central star. No filter. As you increase magnification you may note a bright inner shell around the star, darker shell surrounding it, then bright edge to outer shell. Min. instrument - 80 mm.
NGC 7008 in Cygnus is called the Fetus Nebula, due to its notable shape. It is dim but doable at magnitude 13.3. I star hop with Deneb (Alpha Cygni) and Alderamin (Alpha Cephei) - just a touch over halfway. Use as much magnification as the night allows. You'll see a wealth of detail - a comma shape with a bright knot, an open section with a dark center - almost "breaking" this object in half. Try your Orion Ultrablock filter on this one! Min. instrument - 102 mm.
NGC 7027 is also in Cygnus, and easy to find. Southeast of Deneb are Xi and Nu Cygni, a pair of naked-eye stars that parallel the body of Cygnus. Use them as landmarks to work from. This planetary nebula must be made of kryptonite, as that seemed the color of its bright glow. With enough magnification, you can begin detecting its bi-lobed shape. At mag 8.5 this is a good in-town object. Min. instrument - 1-2 mm.
NGC 6826 is just for fun. In an easy to get to location off Theta Cygni in Cygnus' western wing - you'll know you're there when you come across the obvious equally bright double star WDS 1285. This planetary is one degree east (you can let it drift in!) and appear as a fuzzy star. Magnify until you can see a small "puffy" star. Stare at the central star, and the shell should "disappear". Look away, the star will disappear and the shell reappears. It blinks - hence the name, Blinking Planetary. Min. instrument - 2.5"
NGC 6302 is called the Bug Nebula, and located far south in an easy to locate position near the Stinger in the tail of Scorpius. It has a very high surface brightness, so it's easy to see. Magnify this and note its unusual shape - one "end" bright than the other, and a dark "slash" nearly bisecting it. This target is often overlooked, but you'll want to return to it over and over, in different size telescopes. Min instrument - 110 mm.
If you would like more detailed descriptions, or other targets like these, write me. Or send me your observations. If you have suggestions for articles, I'd like to hear them too.
Mark Wagner is a life-long astronomy enthusiast and deep sky observer. He has spent the past twenty years popularizing amateur astronomy in the San Francisco bay area through his writing and community building. A past president of the San Jose Astronomical Association, he founded what is now the annual Golden State Star Party in California. Please post if you have comments, questions, sketches or images you've taken of the targets mentioned above.