The Equinox 

What Is It?

The equinoxes are the two days each year on which the sun is directly above the Earth's equator. They mark the beginning of fall, and the beginning of spring. The upcoming equinox will be the Vernal Equinox for the northern hemisphere, and the Autumnal  Equinox for the southern hemisphere.

What Difference Does It Make?

Well, as the Earth passes the equinox, all points on the Earth will have 12 hours of sunlight and 12 hours of night. As it APPROACHES equinox, the northern hemisphere's daylight hours are longer than 12 hours, but are decreasing. The southern hemisphere has more night than daytime hours, and their daytime is lengthening.

This change TO more daylight at a more direct angle causes the Northern Hemisphere to experience a warming trend that is the change to Spring. The change to LESS daylight, at a steeper angle, causes the Southern Hemisphere to experience a cooling trend that is Fall, then Winter.

How Do You Participate?

1. Explain the phenomenon to your students. You may want to access the websites I have listed below.
2. Determine how you will gather sunrise and sunset times. If it is from meteorological bureau data, indicate your source.  (** Please strongly caution your students against looking directly at sun, to avoid irreparable eye damage!)

Web Sites to Check Out

Universal times for the vernal equinox

Equinoxes, Solstices, Perihelion, and Aphelion for 1992-2005, U.S. Naval Observatory