CHICAGO — If the colder days haven’t persuaded you it’s winter yet, Thursday might.
Thursday marks the start of the earliest sunset of the year for Chicago, at 4:19 p.m. That sunset time is expected to last through Dec. 15 before slowly getting later through the month, according to SunriseSunset, a website that tracks sunrise and sunset times.
Even as the sun starts to set later — and by later, we mean 4:28 p.m. — the days will get shorter until Dec. 21. That day will have nine hours and 11 minutes of sunlight, making it the city’s “shortest day” of the year.
That’s because even as the sunset time pushes back a couple of minutes, it’s also taking longer for the sun to rise. While it rose at 7:02 a.m. on Tuesday, it will rise 7:14 a.m. on Dec. 21, moving much faster than the sunset time.
These misalignments between sunrise and sunset and between earliest sunset and Chicago’s “shortest day” are because the sun is out of sync with our 24-hour clocks. A solar day can be longer or shorter than a 24-hour day by 30 seconds, according to the Washington Post.
That means the solar noon, which measures the sun’s highest point, can differ from the average by up to 30 minutes on a given day. In the winter months, as the solar noon gets pushed later, the sunrise time is delayed more as the sunset time pushes back, according to the Post. It’s why even after Chicago passes one dark deadline, another looms.
The good news is that the city will never drop below nine hours of daylight — but it will take until Feb.1 for Chicago to see 10 hours of daylight again.
Dark days got you down? Check out our tips for battling seasonal depression here.
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Support Local News!
Subscribe to Block Club Chicago, an independent, 501(c)(3), journalist-run newsroom. Every dime we make funds reporting from Chicago’s neighborhoods. Already subscribe? Click here to gift a subscription, or you can support Block Club with a tax-deductible donation.
Listen to the Block Club Chicago podcast: