Earliest sunsets of the year happening now, before winter
Friday, December 14, 2018, 7:00 AM - It's that time of year when the days feel short, the nights feel long and the sun can sometimes feel like a distant memory.
In the northern hemisphere, we know the winter solstice, which falls on December 21, is the shortest day of the year, but the earliest sunsets of the year actually occur during late November and early December on the days leading up to the solstice and not the start to winter itself.
This has to do with the small difference between mean and apparent solar time.
MEAN TIME VS. APPARENT SOLAR TIME
Mean solar time is what we are most familiar with as it's the time we read on clocks and the average length of one solar day, which we assume as 24 hours.
Apparent solar time measures the direct movements and observations of the sun, it's the time it takes between two successive returns of the sun around the Earth. This gives us the exact time of one solar day, which actually varies throughout the year due to Earth's elliptical orbit and tilt.
Because of the slight difference between mean and apparent time, solar noon (the sun's highest point in the day) will shift slightly earlier on the days preceding the winter solstice, which leads to an earlier sunset.
NO SUNLIGHT AT ALL
For areas north of the Arctic Circle, within 23.5 degrees of the North Pole, there are more than two months of the year when the sun NEVER rises above the horizon. Fairbanks, Alaska will still see a sunrise and sunset at this time of year, but a sunset as early as 2:41 p.m. AKST on the winter solstice leaves less than four hours of sunlight after a late sunrise at 10:58 a.m. AKST.
(MUST READ: This Alaskan town won't see the sun for 65 days)