Astronomical Clock
Astronomical Clock
This Demonstration illustrates the working of an astronomical clock.
To visualize the movement of the Sun and Moon on the celestial sphere, astronomical clocks use stereographic projection. The Earth's projection is at the center of the clock, surrounded by the concentric circles of the Equator and the tropics. The blue ring is the projection of the ecliptic with the Sun and the Moon. The ecliptic ring is divided into sectors defining the four seasons and the 12 months of the year. The red circle is the projection of the horizon dividing the celestial sphere into day and night.
Change the date to show the position of the Sun and the position and phase of the Moon for that day. Change the time to move the ecliptic to its corresponding position around the Earth. Setting the observer's latitude moves the horizon and defines the times when the Sun and Moon will rise or set.