Hubble snaps a glittering globular cluster about 20,000 light-years from Earth

This star-studded picture captured by NASA/ESA Hubble Space Telescope features NGC 671, a globular cluster lying more than 20 000 light-years from Earth in the constellation Sagittarius, which is in the same area of the night sky as the center of our Milky Way

This image is featured in the September edition of the 2022 ESA/Hubble Calendar. It was originally released in September 2021.

1/ In the 2022 ESA/Hubble Calendar the month of September features a glittering globular cluster: the NGC 6717, which lies more than 20 000 light-years from Earth. Free .pdf of the 2022 calendar here: https://t.co/o06kf8lwzU pic.twitter.com/EQpgqDW0pU

— HUBBLE (@HUBBLE_space) September 1, 2022

A globular cluster is a roughly spherical collection of stars tightly bound together by gravity. As visible in this image, globular clusters contain more stars in their centers than their outer fringes - the sparsely populated edges of NGC 6717 are in stark contrast to the sparkling collection of stars at its centre.

Looking to the centre of the image, it contains some interlopers from closer to home. These bright foreground stars reside between Earth and the cluster and are easily spotted by the crisscross diffraction spikes that form when their light interacts with the structures supporting Hubble's secondary mirror, according to ESA.

To determine the properties of NGC 6717, astronomers relied on two of the telescope's powerful instruments - the Wide Field Camera 3 and the Advanced Camera for Surveys (ACS).

The Hubble Space Telescope is a project of international cooperation between NASA and ESA (the European Space Agency). ACS was installed on the telescope during Servicing Mission 3B in 2002 and its wavelength range extends from the ultraviolet, through the visible and out to the near-infrared. The Wide Field Camera 3 or WFC3 was installed during Hubble Servicing Mission 4 in 2009 and it can observe ultraviolet, visible, and near-infrared light.