Globular clusters are densely packed spherical formations of hundreds of thousands or even millions of stars. They are among the oldest known objects in the universe and are predominantly associated with the oldest components of galaxies.
Our Milky Way galaxy contains at least 150 such objects, and several more are likely hidden behind its thick disk. Cluster NGC 6717, which was captured by the Hubble lens, is approximately 7,100 parsecs (23,157 light years) away in the constellation Sagittarius.
This cluster, also known as ESO 523-14 and GCl 105, was discovered by the German-born British astronomer William Herschel on August 7, 1784.
“Globular clusters contain more stars at their centers than at their outer edges, as this image illustrates. The sparsely populated edges of NGC 6717 are in stark contrast to the sparkling cluster of stars at its center.”- Hubble astronomers.
The image consists of observations from the Hubble Wide Angle Camera 3 (WFC3) and the Advanced Research Camera (ACS) in the ultraviolet, near infrared and optical parts of the spectrum.
Image based on data from five filters. Color is obtained by assigning a different hue to each monochromatic image associated with a separate filter.