Fuzzies in Your Future:
An Introduction to Deep-Sky Objects
I see that you're relatively new to backyard astronomy. You own a starter scope and you're getting the hang of using it. You're having fun observing the Moon and planets and maybe double stars, too. If I'm reading the picture correctly, you also want to go after some tougher targets, such as star clusters. . . a nebula or two. . . maybe even a few galaxies. But you're worried that they might be too faint and fuzzy. This is subtle stuff, they say, and you don't know where to begin.
Well, you've come to the right place! Listen closely . . . .
The things you seek are called deep-sky objects. Simply put, the term refers to all celestial objects outside the solar system. In essence, though, we're talking about star clusters and nebulae within the Milky Way, plus the myriad galaxies beyond. (Individual stars, double stars, and
Yes, most deep-sky objects are a challenge to observe, especially if you're working with modest equipment under a suburban sky. So what makes the little fuzzies so special? In a word, it's their exclusivity. When a faint cluster or nebula materializes in the eyepiece of your telescope, you're scrutinizing a part of the Milky Way that might be several thousand light-years from Earth. Gaze upon a galaxy, and the light-years number in the millions.
Allow me to put this in perspective with a brief lesson in galactic geography.
Picture our galaxy as a stellar metropolis containing billions of stars. The central hub, or bulge, is congested with mostly older suns. Away from the hub, the galaxy thins into a disk of gas, dust, and stars of all ages. Rippling through the disk like ocean waves, a pinwheel pattern of glowing spiral arms hosts the youngest stars and the nebulae associated with their births. Our middle-aged Sun and its family of planets reside in a suburban neighborhood called the Orion Arm, which is located roughly two-thirds of the distance from the downtown core to the city limits. Finally, in the galactic outskirts, a vast halo dotted with clusters of ancient stars surrounds the whole galaxy.
Viewed from Earth, portions of several spiral arms blend together in our night sky to form the arching band of the Milky Way. Deep-sky treasures abound in and around that glittering band. Click ahead to the next section, and I'll conjure up some examples for you.