Today, we’re off to the Equinox—not just a trendy, overpriced gym, but also one of two moments each year when the sun is directly overhead the equator.It happen
Today, we’re off to the Equinox—not just a trendy, overpriced gym, but also one of two moments each year when the sun is directly overhead the equator.
It happens at 5:05 p.m., officially turning a page in our seasonal book to the autumn chapter.
As we learned in elementary school, equinox comes from Latin for “equal night,” suggesting exactly 12 hours of day and 12 hours of night. But Seattle actually gets a dime extra: 12 hours and 10 minutes of daylight.
Where do those extra 10 minutes come from? Two things:
1.Sunlight refracts—or bends—through the atmosphere at low angles, letting us "see" the sun momentarily just before it actually rises above the horizon, and just after it has slipped below.
2.The sun is a disc, not a point. It takes a little extra time for the whole thing to rise and set.
That net + daylight effect is even bigger at higher latitudes, so Fairbanks gets more equinox daylight than Seattle—and Seattle gets more than the equator.
At the equator, day length barely changes all year: roughly 12 hours and a few minutes each day of the year - never ever slipping below that 12-hour mark!
