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    Later sunsets from the Equation of Time
    From: Frank Reed
    Date: 2014 Jan 9, 14:47 -0800

    Looking out the window as I write this, it's twilight. A few weeks ago at this time of the early evening, about 5:15pm EST here in Rhode Island, it was dark. Why is that?

    The days are getting longer right? Yes. But that's only half the story. This time of the year during December and January, the Sun is falling behind. It's lagging every day by about 24 seconds as the equation of time swings from its fast peak in early November to its deep, slow valley in early February. The Sun will reach the meridian four minutes later ten days from now compared to today. The days are getting longer, but the Sun is falling behind, and that means that sunset is falling later in the afternoon at twice the pace that would be realized if this was due to the days getting longer alone. And the other side of the coin is that sunrises are hardly changing at all. Two week ago here, the Sun rose at 07:11 in the morning, and today it also rose at 07:11. But sunset moved ahead from 16:22 to 16:34. Two weeks from now, the Sun will set half an hour later than it set on the solstice (Dec. 21), but sunrise will happen only four minutes earlier. The equation of time is your friend! ...unless you're a morning commuter.


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