Equal Night: The Vernal Equinox
Today is the vernal equinox for those of us in the northern hemisphere; the autumnal equinox for those in the southern hemisphere. The equinox is the twice-yearly event in the earth’s orbit around the sun when the sun’s rays reach all parts of the globe equally. The word “equinox” is from the Latin roots “equi” and “nox” meaning “equal night.” The equinox has “equal night” in two senses. First the length of the night (and the day) is about equal all over the globe on this date. Second, the hours of light and hours of dark are approximately equal, at about 12 hours each.
The table below shows sunrise and sunset times today for a selection of locations around the world. As you can see, the length of day (and night) for every one of these places is close to 12 hours. I was surprised to discover, however, that none of these locations had exactly equal hours of day and night (12 hours each) on the equinox. Instead, places in the northern hemisphere had their 12-hour day and 12-hour night 2-5 days (depending on location) before the equinox, and those in the southern hemisphere will have their 12-hour day and 12-hour night 2-5 days after the equinox.
|Location||Sunrise||Sunset||Length of day|
|Poland, Maine (US)||6:45||6:53||12:8|
|Gettysburg, Pennsylvania (US)||7:12||7:21||12:9|
|Naples, Florida (US)||7:31||7:38||12:7|
|Seattle, Washington (US)||7:12||7:21||12:9|
|Los Angeles, California (US)||6:57||7:04||12:7|
|Kotzebue, Alaska (US)||8:50||9:05||12:15|
|Whitehorse, Yukon (Canada)||8:02||8:14||12:12|
|Toronto, Ontario (Canada)||7:21||7:29||12:8|
|Kuala Lumpur, Malaysia||7:17||7:24||12:7|
|Cape Town, South Africa||6:50||6:58||12:8|
|Christchurch, New Zealand||7:32||7:42||12:10|
|Buenos Aires, Argentina||6:57||7:05||12:9|
|McMordo Station, Antarctica||7:43||8:18||12:35|
For those who garden near the equator, days and nights are close to equal all the time, and the equinox is not a major event. But the further away from the equator we travel, the greater the difference in length of day as we move from solstice to equinox to solstice. For many who garden in northern latitudes, the vernal equinox marks the psychological beginning of the garden season. Even if we still have snow in our gardens or the still-thawing ground is much too soggy to work, this is the point in the year when hours of daylight become longer than hours of darkness. From now until the summer solstice, as our part of the earth tilts toward the sun, the days will just keep getting longer and longer and the temperatures milder and milder. Plants will spring up and bloom, and the barren garden scene of winter will turn lush and green.
Let the gardening begin!