Gnomon Model is a handy, Java based application designed to simulate the shadow cast by a gnomon (the part of a sundial that casts the shadow) over the course of a day for any day of the year and any latitude on Earth.

The program gives you the option to use mean Sun (which moves relative to the stars at a constant rate throughout the year) or true Sun (which varies its apparent speed relative to the background stars). The default is to use true Sun. The program also shows the observer's horizon plane on the spherical Earth, as well as the ecliptic and the apparent path of Sun. The Earth View can be set to let Earth rotate or remain fixed