Caption: The explanation of the seasons illustrated by NAAP applet: Seasons and Ecliptic Simulator .

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Features:

1. Just push all the buttons and see what they do to gain insight.
2. Left click to drag the celestial sphere orientation.
3. Drag the red needle to change the month.
4. You can drag the solar noon observer to different latitudes. In the tropics (i.e., between Tropic of Cancer (23°26'12.0'' = 23.43668° N, c.2017) and Tropic of Capricorn (23°26'12.0'' = 23.43668° S, c.2017)), the applet shows that the Sun will be at zenith at solar noon twice per solar year = 365.2421897 days (J2000), except only once per solar year = 365.2421897 days (J2000) exactly on the tropic lines themselves. When the Sun is at zenith, there is vanishing little shadow, except straight down from an object casting a shadow. Outside of the tropics, the Sun never gets to zenith. Ecuador is a strange place.

The terms in the applet need some explanation. As you feel the need, click on any of the keywords in Celestial sphere keywords below (local link / general link: celestial_sphere_keywords.html):

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