The first day of Spring is on Sunday, March 20, 2011. This day is also know as the Vernal Equinox, because it heralds the beginning of the spring season for Earth’s northern hemisphere.
At the instant of vernal equinox, the sun lies in the plane of Earth’s equator. As a consequence, days and nights are of equal length (12 hours each) everywhere on our planet. Another consequence is that the sun rises due east along the horizon and sets due west. During the next three months, as the sun shines more and more directly on our hemisphere, daylight hours will lengthen and the rise and set positions of the sun will gradually shift toward the northeast and northwest, respectively.