Deep Sky Objects

"Deep sky objects" (DSOs) are astronomical objects beyond our solar system that are not individual stars.

Types of Deep Sky Objects

• Star clusters - Gravitationally bound groups of stars (open clusters, globular clusters).
• Nebulae - Clouds of gas and dust (bright nebulae, dark nebulae, planetary nebulae).
• Galaxies - Vast systems of stars, gas, and dust beyond our Milky Way.

Observing Deep Sky Objects

Most DSOs require binoculars or telescopes to see. They appear as faint, fuzzy patches to the eye, but long-exposure photography reveals stunning detail.

Messier Catalog

Charles Messier compiled a list of 110 nebulous objects in the 18th century to help comet hunters avoid confusing them with comets. Today the Messier catalog is a popular observing list for amateur astronomers.

NGC and IC

The New General Catalog (NGC) contains nearly 8,000 objects. The Index Catalog (IC) adds more. Most bright DSOs have NGC or IC numbers (e.g., NGC 7009 = Saturn Nebula).