For those interested in learning more quickly, here are some sites with excellent explanations of the soul and the substance of amateur deep-sky observing:
Perhaps the most natural dividing line in all of astronomy is that between objects which are gravitationally bound to Earth's Sun on the one hand (the so-called "Solar System objects"), and everything which isn't on the other. We know many objects to be our fellow-travellers in orbit around the Sun: these include eight known planets (excluding Earth), all of their moons (including our own Luna), dizzying numbers and types of asteroids, long- and short-period comets, "meteoroids" (the specks of dust that cause shooting stars), "zodiacal dust" - and of course the Sun and Earth themselves!
Beyond the gravitational grasp of Sol however, lies a vast well of emptiness, reaching all the way to the nearest stars, and then far, far beyond. Inhabiting this daunting vastness are a whole unearthly menagerie of different objects - essentially all of which can be seen with your own eyes, if you have a little knowledge and skill!
This menagerie of visible objects in the depths of space are what amateur astronomers call "the Deep Sky". Of course, Deep Sky objects fall into categories as well! For amateurs, these categories tend to tell us something about how to observe individual objects, and (perhaps more importantly for our passion) what the real NATURE of these tiny, faint objects is...
Here are some of the basic types of objects which we amateurs love to observe in the Deep Sky, along with links to more info about each!
| Open Clusters | Globular Clusters | Multiple Stars | Variable Stars |
| Planetary Nebulae | Bright Nebulae | Dark Nebulae | Supernova Remnants |
| External Galaxies | Galaxy Clusters | Galaxy Groups | Quasars and Lenses |
To find out more about the Deep-Sky take advantage of some of the wonderful resources available on the Web, including: