More day than night at the equinox
Over the years, I’ve heard from many people who incorrectly assume that on the day of the equinox, we enjoy exactly 12 hours of daylight and 12 hours of darkness. Not quite.
By the time you read this, unless you’re a very early riser, it will be spring! The vernal equinox took place before sunrise today across the Maritimes, and almost exactly at sunrise in Newfoundland and Labrador.
The word “equinox” comes from the Latin words for “equal night.” Equinoxes are not daylong events, even though many choose to celebrate all day. Instead, they occur at the precise moment the Sun crosses the celestial equator – the imaginary line in the sky above the Earth’s equator. At this instant, Earth’s rotational axis is neither tilted away from, nor towards the Sun.
Over the years, I’ve heard from many people who incorrectly assume that on the day of the equinox, we enjoy exactly 12 hours of daylight and 12 hours of darkness. Not quite. While you were celebrating St Patrick’s Day on Wednesday, you could also have been raising a glass to equal day and night. Today, we get to enjoy approximately 12 hours and 10 minutes of daylight.
Here’s why: Sunrise is defined as the moment the top edge of the sun appears to peek over the horizon. Sunset is when the very last bit of the sun appears to dip below the horizon. The vernal and autumnal equinoxes, meanwhile, occur when the center of the sun’s disk crosses what’s known as the celestial equator. According to former astronomer, George Greenstein, “If the Sun were to shrink to a star-like point and we lived in a world without air, the spring and fall equinoxes would truly have ‘equal day and night’.”
Of course, Grandma must weigh in. She and many of our ancestors believed that the wind direction at the precise moment of the equinox could foretell the weather for the summer.
If the wind was from the south, summer would be warm. A north wind pointed to a cold summer. An east wind would indicate a damp summer and a west wind meant it would be dry. You’ll have to fill me in, but the forecast wind direction at the time of publication was west to northwesterly right across the region.
Here are today’s equinox times: 6:36 a.m. ADT and 7:06 a.m. NDT. Let me know what kind of summer Grandma thinks you will have this year.