In this section, we will use the Stereographic projection and a star catalog to create an interactive celestial map. The Stereographic projection displays the sphere as seen from inside. A star map created with the Stereographic projection is shown in the following screenshot:

Celestial coordinate systems describe positions of celestial objects as seen from Earth. As the Earth rotates on its axis and around the Sun, the position of the stars relative to points on the surface of the Earth changes. Besides rotation and translation, a third movement called precession slowly rotates the Earth's axis by one degree every 72 years. The Equatorial coordinate system describes the position of stars by two coordinates, the declination and the angle from the projection of the Earth's equator to the poles. This angle is equivalent to the Earth's longitude. The right ascension is the angle measured from the intersection of the celestial equator to the ecliptic, measured...