Desperate for a clear night to image, I was suckered out by a break in the cloud cover that left the entire sky clear just long enough for me to get the telescope set up and aligned and the camera ready. By the time I had all that done, the clouds began moving back in and very soon covered the entire sky. There was time to capture only one image, so I opted for the brightest object then convenient situated in the sky – one that would require a short exposure time.
M3
This image is comprised of about 20, 15-second sub-exposures, for a total five minute exposure. It is one of the better images of M3 that I have obtained.
M3 is a massive globular cluster, one of the brightest in the skies over the northern hemisphere, eclipsed in beauty and fame only by the great globular cluster in the constellation Hercules, M13. A globular cluster is a dense sphere-shaped cluster of stars, bound together by strong gravitational attraction. The stars in these clusters tend to be quite old and metal-poor, suggesting that most globular clusters are formed in a galaxy's early youth. Globular clusters are usually found in a galaxy's halo – outside the main plane of a spiral disk. The Milky Way is known to have 151 globular clusters, but it is estimated that there are probably 20-30 more that are occluded by the dust and gas of our galaxy's spiral arms and are thus not visible from Earth. Globular clusters have been spotted in many distant galaxies
M3 lies about 33,900 light years from Earth. Located in the constellation Bootes, it is easily glimpsed as a round, hazy patch with good binoculars; a telescope is needed to resolve it into a dense cloud of stars, concentrated at the center. The cluster was first discovered by Charles Messier in 1764, but was not identified as a star cluster until William Herschel's superior telescope resolved it twenty years later.
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