I always understood that the vernal equinox was not only one of two days in the year in which the Earth wasn't tilted towards or away from the sun, but also a day in which the same amount of time elapsed between sunrise and sunset as between sunset and sunrise. When I checked the sunrise data on the US Naval Observatory webpage, they show that date as having happened on Saturday, March 17. I was about to celebrate the equinox with my class tomorrow when I realized the difference, and now I want to be sure before I tell them something that isn't correct.
Posted March 20, 2007
Also, from Tom: "Just curious why it is that we already have more than twelve hours of daylight and the equinox is not until tomorrow?"
MIKE MOSS SAYS: Debbie and Tom, I addressed this particular subject in Monday's WeatherCenter Blog. You can read it by clicking the "Weather Blog" link in the Weather Data section on our main weather page, or go directly to this address:
Hope that helps!