Final answer:
The region referred to is the galactic bulge, a dense concentration of stars at the center of the Milky Way Galaxy, distinguishable by its brightness and population of older stars.
Step-by-step explanation:
The bright, sphere-shaped region of stars that occupies the central few thousand light-years of the Milky Way Galaxy (MWG) is known as the galactic bulge or sometimes referred to as the central bulge or nuclear bulge. It is this dense concentration of stars that contributes to the prominent brightness seen when observing the center of our galaxy.
The galactic bulge is distinct from the thin disk of the Milky Way, which spans about 100,000 light-years in diameter and is approximately 2000 light-years thick. The bulge forms a stark contrast as it contains a greater density of older stars and can be observed in certain areas that are less obscured by interstellar dust, especially when viewed at infrared wavelengths.
Understanding the structure of the galactic bulge, along with other components such as the thin disk and globular clusters like Messier 80, is crucial for astronomers trying to determine the mass and the distribution of stars in the MWG. The central bulge forms an essential part of our galaxy's overall structure, influencing the dynamics and evolution of the stars within it.