Amateur astronomers like to target deep-sky objects with their telescopes. The Ring Nebula, M57, in the constellation Lyra, is one such target. The white dot in the center of this nebula is a white dwarf. This planetary nebula came from a star that was once like the sun. Image via The Hubble Heritage Team (AURA/ STScI/ NASA).
What are deep-sky objects?
Deep-sky objects lie beyond our solar system and make great observing targets for those using optical aid under dark skies. Amateur stargazers sometimes refer to them as faint fuzzies. Unlike the nearby planets (which look like little disks through a telescope) or stars (which always look like pinpoints), deep-sky objects are hazy spots in the sky that start to take shape when viewed through binoculars or a telescope. Deep-sky objects generally fall into three categories: nebulae, galaxies and star clusters, including open clusters and globular clusters.
Some of the best deep-sky targets are those in the Messier catalog. Charles Messier was a comet hunter who methodically searched the skies for comets. He cataloged all objects that were not comets, but might be confused with them because they looked fuzzy.
He didn’t know it at the time, but he ...