Which astronomer first mapped the shape of the Milky Way in the 18th century?

The astronomer who first mapped the shape of the Milky Way in the 18th century was William Herschel.

In 1785, Herschel attempted to determine the Galaxy’s structure by systematically counting stars in different parts of the sky. From these star counts, he produced a model showing the Milky Way as a flattened, disk-like system. His diagram also placed the Solar System near the center, an important conclusion that later observations proved incorrect.

Herschel’s work was pioneering because it treated the Milky Way as a structure that could be measured rather than merely described by its appearance in the night sky. He built powerful telescopes and carried out extensive surveys of stars, nebulae, and clusters. He is also famous for discovering Uranus in 1781 and for detecting infrared radiation.

Later astronomers, especially Harlow Shapley, demonstrated that the Sun is far from the Galactic Center by studying the distribution of globular clusters. Herschel therefore made the first observational model of the Milky Way’s shape, but not the first accurate map of its true dimensions or the Sun’s location.