Object Analysis

The Omega Nebula (Messier 17), also known as the Swan Nebula, Checkmark Nebula, and Horseshoe Nebula, is an H II region in the constellation Sagittarius. It is located between 5,000 and 6,000 light-years from Earth and spans about 15 light-years in diameter. The nebula is considered one of the brightest and most massive star-forming regions of our galaxy.

Its open cluster of stars, NGC 6618, is embedded in the nebulosity and causes the gases of the nebula to shine due to radiation from these hot, young stars. The number of stars in this cluster is estimated to be 800, while the nebula itself is estimated to contain enough gas to form thousands more stars.

To the observer, M17 appears as a distinct bar or checkmark shape, which represents the neck and body of the "swan." It is visible with binoculars in dark skies and reveals intricate smoky details in large telescopes. Its vivid red color in photographs comes from ionized hydrogen gas.