In 1665, whereas observing Saturn (which was positioned in Sagittarius on the time), German astronomer Johann Abraham Ihle stumbled on an sudden sight. Simply over 2° northeast of Third-magnitude Kaus Borealis (Lambda [λ] Sagittarii) on the high of the Teapot asterism, he discovered a small, nebulous patch. Though he had no concept what he had seen, Ihle had unintentionally found the primary globular cluster. As we speak, we all know it as M22.
The Hercules Cluster (M13) could also be thought of one of many most interesting globular clusters within the night time sky, however it will get stiff competitors from M22, which seems bigger and a half-magnitude brighter than its Herculean counterpart. That obvious superiority, nevertheless, is an phantasm brought on by disparate distances. M22 is little greater than 10,000 light-years away — lower than half the space to M13.
Regardless of M22 containing lower than half the celebrities of M13, it nonetheless proves simpler to resolve. A 3.5-inch scope is all it takes to identify not less than some stars across the fringes. An 8-inch is greater than sufficient to show a large number of faint stars strewn throughout the whole cluster.
Make a sluggish, cautious research of M22, noting its general form. Most globular clusters are spherical, however not M22. It’s elliptical, with the lengthy dimension angled northeast-southwest. This odd form is clear by practically all scopes and even in bigger binoculars.
Of the 150 identified globular clusters related to the Milky Way, M22 is one in every of solely 4 that accommodates a planetary nebula. In 1985, NASA’s Infrared Astronomical Satellite tv for pc uncovered a mysterious infrared supply among the many cluster’s stars. After 4 years of analysis, astronomers confirmed that the supply was a planetary nebula positioned 1′ south of the cluster’s middle.
Discovering this planetary, generally known as GJJC 1, takes an aperture of not less than 20 inches. The most effective seeing situations are additionally a should, as a result of not less than 600x is required to make out the planetary’s tiny disk.
Make certain to discover Astronomy’s full list of 101 cosmic objects you must see. New entries will probably be added every week all through 2022.
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