Vernal Equinox

1. The length of the sun's midday shadow changes, because the earth is rotating around the sun in different positions throughout the day. The sundial reflects this in it's shadows.
2. On the equinox, the sun's apparent position is directly above the equator.
3. The shadow would be at it's shortest at noon on the Vernal Equinox.
4. The angle of the shadow could be measured by using the equation tan.
5. On the equinox, the angle of the sun's shadow, at midday, would be 90 degrees.