Why Aren't The Sunrise And Sunset Equal On The Equinox?

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By By Steve Pool

SEATTLE - The first days of spring and fall are a time when there is equal 12-hour daylight across the planet. However, looking at a Seattle sunset chart shows Seattle has 12 hours and 11 minutes of daylight on Sept. 21. Why?

Sunrise and sunset are calculated when the top of the sun is on the horizon. However, equal daylight is measured from the center of the sun -- accounting for a few minutes. The other discrepancy is from when the sun is on the horizon, the Earth's atmosphere bends the sun's light.

As a result, the sun still looks to be above the horizon for a few minutes after it has already set. The U.S. Naval Observatory takes this into consideration when calculating sunrise and sunset times.

For More Information -- www.usatoday.com

Your Photos

YouNews November 26th November 26th
Less than two weeks ago it was single digits here, probably made it into the low 40's the past few days. Lilac has new buds all over it and this one has started to grow.
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These images of the sunrise with Mt. Rainier were taken around 8am Monday November 24th. The pictures were taken with a Nikon D3000 DSLR with a 50-200mm telephoto lens.