In 1784 astronomer William Herschel discovered the globular cluster NGC 6638 by an 18.7-inch telescope and later in the New General Catalog, NGC 6638 is a globular cluster located in the constellation Sagittarius, Hubble’s image showing the heart of this globular cluster NGC 6638 shows. The stars are scattered throughout this globular cluster, and for observation, researchers shed light on the star density at the center of NGC 6638, where the stars are stable and tightly bound, a cluster of thousands to millions of stars.
To capture the image of NGC 6638, researchers used two of Hubble’s state-of-the-art astronomical instruments, the Wide Field Camera 3 and the Advanced Camera for Surveys, Hubble has been instrumental in helping scientists understand the globular cluster. It is impossible for ground-based telescopes to clearly distinguish the stars in the core of the globular cluster NGC 6638, as it is not possible to see clearly in distortion caused by Earth’s atmosphere.
It is not possible to clearly see globular clusters with any ground-based telescopes, so researchers enlisted the help of Hubble, because Hubble can study any objects orbiting the Earth about 340 miles (550 km) above, The Hubble Telescope has these properties, that it can reveal, what kind of stars form globular clusters, how they develop. After the Hubble Telescope, the James Webb Space Telescope will study globular clusters, webb can see star-studded interiors, which are not possible to see by Hubble, because the Webb telescope observes any object at infrared wavelengths.