Las Vegas to see earliest sunset of 2020, but not least amount of daylight

Posted at 12:34 PM, Dec 02, 2020
and last updated 2020-12-02 15:44:33-05

LAS VEGAS (KTNV) — Something interesting is happening in the sky tonight, though it's easy to miss when distracted by the hustle and bustle of everyday life.

Beginning Wednesday, Dec. 2, Las Vegas will experience the earliest sunsets of the year each day through Monday, Dec. 7, when the sun will go down at 4:25 p.m. local time.

But, that doesn't mean the city will have the least amount of sunlight on those days.

The winter solstice, which signifies the least amount of daylight of the entire year, isn't until Dec. 21.

Furthermore, the latest sunrise of the year doesn't happen until after the winter solstice, from Jan. 4 through Jan. 8, at 6:52 a.m. local time.

So how is that possible?


If it seems odd that the latest sunrise of the year and the earliest sunset of the year don't happen on the shortest day of the year, you're not alone!

It's a bit complicated but boils down to the fact that on the solstice the Earth is tilted farthest from the sun.

It takes 24 hours and 30 additional seconds to complete our daily rotation around the Earth's axis on the solstices, both in winter and in summer.

On the flip side, on the equinox when the Earth's axis is parallel with the sun -- and the days and nights are equal -- it takes a little less than 24 hours for the Earth to complete a rotation.

It's tough to visualize, but because the clock consistently measures our days as 24 hours long, there is a lag that occurs with the earliest sunsets that places them before the solstice, and a similar lag that occurs with the latest sunrises that places them after a solstice.

Also at play, because we measure sunrise as when the top of the sun crosses the horizon and the sunset when the top of the sun falls below the horizon, even on the equinox it's not perfectly equal day versus equal night.

One final tidbit: the winter solstice in the Northern Hemisphere falls on the perihelion, the point in its orbit when the Earth is closest to the sun, and therefore moving fastest, thanks to gravity.