👉 A planisphere is a type of celestial sphere or disk, often used in astronomy for representing and visualizing the Earth's orbit around the Sun. Planispheres are circular disks that have a uniform radius and are not curved like other celestial objects such as moons or planets. In terms of its mathematical representation, a planisphere is defined by two concentric circles with radii \(r_1\) and \(r_2\), where \(r_1 < r_2\). The center
