Phoenix's earliest sunset arrives early December, defying solstice timing

PHOENIX — Here’s a sure sign of the changing season: The earliest sunset of the year! In Phoenix, the sun slips below the horizon in early December right around 5:20 p.m.

However, you might notice what seems to be a discrepancy. The shortest day of the year hits on the winter solstice, which is December 21 — but the earliest sunset shows up three weeks earlier.

So what’s going on? How can the sunset start getting when the days are supposed to be getting shorter?

It turns out the Sun isn’t nearly as tied to our clocks as we like to think. While our days are a strict 24 hours, the Sun’s schedule shifts a little because of two things: Earth’s tilt and the fact that our orbit is slightly oval. Those two quirks make the length of a “solar day,” the time from one true noon to the next, change