Johannes Hevelius was a 17th-century Polish astronomer known for his detailed observations of celestial bodies. Born in 1611 in Gdansk, he built one of the largest observatories of his time, where he conducted extensive studies of the moon, stars, and planets. Hevelius is particularly famous for his work on lunar maps and for cataloging over 1,500 stars. Hevelius published several influential works, including Machina Coelestis, which detailed his astronomical instruments and methods. He was also one of the first to use the telescope for serious astronomical research. His contributions laid the groundwork for future astronomers, including Isaac Newton and Christiaan Huygens.