Next applet shows the earth. The yellow meridian circle separates the parts that are lightned up by the sun from those that aren't. [br][list][*]You can modify the [b]axial tilt[/b] by dragging the north pole. [/*][*]You can modify the [b]latitude[/b] by dragging the green point on its meridian.[/*][*]You can modify the [b]time[/b] by dragging the blue point on the equator.[/*][*]The yellow arrow marks the [b]angle of incidence[/b] of the sun.[br][/*][/list]