The yellow circle is the image point (Geographical Position) of the sun, where the line from the sun to the center of the earth intersects it's surface. The coordinates (latitude and longitude) are the same as the declination and Greenwich-Hour-Angle (GHA) of the sun. An observer positioned in the Geographical Position of a star will see the sun directly in the vertical, above his head.

A click into the map dispays the coordinates, the shadow of a 50 pixel vertical gnomon, and the elevation of the sun.

HTML Applet Tag:

<APPLET CODE="DayNightxxx.class" archive="applet/JavaClasses.jar" NAME="Day & Night" WIDTH=500 HEIGHT=290 ALIGN=bottom>
</APPLET>