Deep-Sky Objects

Deep-sky objects can be loosely defined as all objects outside our solar system that consist of more than a single star system or involve nebulosity. The deep-sky objects most popular with amateur astronomers are star clusters both open and globular, nebulae, and galaxies.

Deep-sky viewing can be challenging. A dark sky is essential, because most of these objects are faint and diffuse. A few can be seen with the naked eye. Binoculars pointed at the various sections of the Milky Way will reveal many small hazy patches, mostly open star clusters. Telescopes of increasing aperture will bring hundreds or thousands of objects into view, most of them galaxies at the very edge of visibility.

Finding deep-sky objects is not trivial and requires a thorough knowledge of the sky. Some of the more expensive telescope options are computers that allow a user to "dial in" the celestial coordinates of a selected object, but most deep-sky observers delight in the fun of the chase. Star-hopping is the most frequently used method. An observer becomes familiar with the naked-eye stars in an area, and then uses them to point the way to an object visible in binoculars or a telescope. A star atlas is essential for making one's way through a field of faint stars to find a fainter object. Deep-sky observers have the most to gain by staying away from light pollution and allowing their eyes to dark-adapt.

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