This spectacular star-studded image shows the heart of the globular cluster NGC 6638 in the constellation Sagittarius. Captured by the NASA/ESA Hubble Space Telescope, this star-strewn observation highlights the density of stars at the heart of globular clusters, which are stable, tightly bound clusters of tens of thousands to millions of stars. Hubble used two of its cutting-edge astronomical instruments to capture the data in this image: Wide Field Camera 3 and the Advanced Camera for Surveys.
Since it is almost impossible to clearly distinguish the stars in globular clusters with ground-based telescopes, Hubble revolutionized the study of globular clusters. Earth’s atmosphere causes blurring that makes it impossible to tell one star from another, but from Hubble’s location in low Earth orbit, the atmosphere is no longer a concern. As a result, Hubble has been used to investigate what kind of stars globular clusters are made up of, how they evolve, and the role of gravity in these dense systems.
Now, with the NASA/ESA/CSA James Webb Space Telescope, we will improve our knowledge of globular clusters by peering into those globular clusters that are currently obscured by dust. Webb will primarily observe at infrared wavelengths, which are less affected by the gas and dust surrounding newborn stars. This will allow astronomers to inspect star clusters that are freshly formed, providing insights into stellar populations before they have had a chance to evolve.