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upcoming solstice brings the shortest day and longest night of the year. And yet the earliest sunsets for middle latitudes in the Northern Hemisphere are happening around now.
• It seems paradoxical. At middle latitudes in the U.S. - and throughout the Northern Hemisphere - the earliest sunsets of the year come about two weeks before the solstice and the shortest day of the year.
• Why isn't the earliest sunset on the year's shortest day? It's because of the discrepancy between the clock and the sun. A clock ticks off exactly 24 hours from one noon to the next. But an actual day - as measured by the spin of the Earth, from what is called one "solar noon" to the next - rarely equals 24 hours exactly.
• Solar noon is also called simply "midday." It refers to that instant when the sun reaches its highest point for the day. At this time of year, the time period from one solar noon to the next is actually half a minute longer than 24 hours. Today, the sun reaches its noontime position at 11:52 a.m. local standard time. Two weeks from now - on the winter solstice - the sun will reach its noontime position around 11:59 a.m. That's 7 minutes later than today.
• The exact date for the earliest sunset or earliest sunrise varies by latitude. At present, mid-temperate latitudes in the Northern Hemisphere have their earliest sunsets, while the Southern Hemisphere's mid-temperate latitudes are waking up to their earliest sunrises. At latitudes closer to the equator, the earliest sunset or earliest sunrise has already come and gone. Closer to the Arctic and Antarctic Circles, the earliest sunset and earliest sunrise have yet to come.
(Continued on page 21)
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