Johann Heinrich von Mädler was a German astronomer born on April 29, 1794, in Berlin. He is best known for his work on the planet Mars and for creating detailed maps of its surface. Mädler's observations contributed significantly to the understanding of planetary features and helped advance the field of astronomy in the 19th century. In addition to his studies of Mars, Mädler also worked on the measurement of the Earth's rotation and the determination of the positions of stars. He published several important works, including a comprehensive star catalog, which aided future astronomers in their research and exploration of the night sky.