Wednesday, May 27, 2015

Earliest Sunset was Tonight: Happy Seculus Eve!

a reader names tomorrow a new holiday in light of the earliest sunset of the year

Earliest Sunset was Tonight: Happy Seculus Eve!

Reader Howard Wilk wrote to remind me that while the winter solstice is still almost two weeks away, tonight we in Philadelphia and others at our latitude will see the earliest sunset of the year. He has decided to name tomorrow a new holiday in honor of the now-lengthening evenings:   

"The winter solstice marks (for us) the shortest day (light hours), but it's not our date this Dec.-Jan. for the latest sunrise, which will be 5 January, or our date for the earliest sunset, which is today, Thursday, 8 December. Since night owls like me routinely experience sunset but not sunrise, today is effectively the shortest day for us. With a clock but without specific astronomical knowledge one doesn't know one has reached the day of the earliest sunset until the next day, when the sun sets later than the day before. That's a cause for celebration and I call that day, the day after the day of the earliest sunset, Seculus. Seculus is a secular holiday completely divorced from religion unlike Christmas, Hanukkah, Saturnalia, etc., or even Festivus (which is defined as 23 December, two days before Christmas)."

This report in backs Wilk on the date. The sun set tonight at 4:35 and on the Winter Solstice, which is Dec. 22 this year, it will set at 4:39. Earthsky has a nice explanation for this gap between Seculus and Solstice:

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.


About this blog
Faye Flam - writer
In pursuit of her stories, writer Faye Flam has weathered storms in Greenland, gotten frost nip at the South Pole, and floated weightless aboard NASA’s zero-g plane. She has a degree in geophysics from the California Institute of Technology and started her writing career with the Economist. She later took on the particle physics and cosmology beat at Science Magazine before coming to the Inquirer in 1995. Her previous science column, “Carnal Knowledge,” ran from 2005 to 2008. Her new column and blog, Planet of the Apes, explores the topic of evolution and runs here and in the Inquirer’s health section each Monday. Email Faye at Reach Planet of the at

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