Hubble's image of Messier 3 reveals what astronomers say is one of the prettiest "globular clusters" in the universe.
In 1758, the chief astronomer of the Marine Observatory in Paris, Charles Messier, was observing a comet when he became distracted by a cloudy something in the constellation Taurus. Messier made a note of the object to help other comet hunters avoid becoming distracted by it. Commonly known today as M1 (Messier 1) or the Crab Nebula, it became the first object in Messier’s Catalog of Nebulae and Star Clusters, a listing of comet-like "objects to avoid."
By the time of his death in 1817, Messier's list included 103 diffuse objects in the night sky that could be mistaken for comets. The catalog contains galaxies, planetary and other types of nebulae, and star clusters. Fast-forward two centuries and astronomers are working to make images of the catalog's objects with the help of the Hubble telescope. Why? Because as NASA notes, "the Messier catalog includes some of the most fascinating astronomical objects that can be observed from Earth’s Northern Hemisphere."
The third such object on the list, Messier 3, is a globular cluster – as can be seen in the Hubble image above. The European Space Agency (ESA) notes:
Globular clusters are inherently beautiful objects, but the subject of this NASA/ESA Hubble Space Telescope image, Messier 3, is commonly acknowledged to be one of the most beautiful of them all.
At 8 billion years old, this "cosmic bauble" includes an astonishing half-million stars, making it one of the largest and brightest globular clusters ever discovered.
"However, what makes Messier 3 extra special is its unusually large population of variable stars," writes ESA, "stars that fluctuate in brightness over time. New variable stars continue to be discovered in this sparkling stellar nest to this day, but so far we know of 274, the highest number found in any globular cluster by far."
Aside from the abundance of variable stars, Messier 3 also plays home to a relatively high number of "blue stragglers," which can be seen in the image. "These are blue main sequence stars that appear to be young because they are bluer and more luminous than other stars in the cluster," notes ESA.
While it took Hubble to reveal the details of this virtual storm of gemstones, many of the other objects in the Messier catalog are bright enough to be seen through a small telescope, making the catalog's illustrious items popular targets for amateur astronomers of all levels. What Mother Nature provides on our home planet is magical enough; that we can look to the heavens and see such wonders is the icing on the cake ... as well as a great reminder not to lose the nighttime sky.
You can see Hubble's images of other objects listed by Messier here.