Breaking News
More () »

Why we just had the earliest sunset of the year

The earliest sunset of the year happened a full two weeks before the shortest day of the year.

DENVER — The earliest sunset of the year happened on Wednesday, Dec. 7. That means the sun will stay up longer starting Dec. 8.

So, how did the earliest sunset of the year happen a full two weeks before the shortest day of the year — the winter solstice?

It’s mainly because of the way the earth orbits the sun in an elliptical shape instead of a circle.

That causes us to move around the sun at different speeds throughout the year. Faster in the winter (or at least covers more ground) and slower in the summer.

So, the sunsets basically get ahead of schedule. In the summer, the latest sunset occurs about a couple weeks after the summer solstice.   

Credit: KUSA

Another interesting way to visualize that is looking at a time series photo of the sky. If you took a picture of the sun at exactly the same time and place every day for a year, you would see a figure eight pattern called an analemma. 

The size of the loops shows the change in speed.  

Credit: J. Fishburn - Wiki Commons

There’s a longer loop in the winter when the earth is moving faster. The earliest sunset is shown right before sun reaches its southern-most point on the horizon known as the winter solstice. 

The sunset on Dec. 8 will only be about two seconds later than it was on Wednesday. Then the sun will gradually stay up longer each evening, gaining a little more than three minutes of daylight (at least in the evening) by the winter solstice on Dec. 21.

But the morning sunrises are also happening later, so the total length of daylight is still decreasing. Right after the winter solstice, the evening sunsets will finally be late enough to start lengthening the days.

The days will get a little longer each day until the summer solstice in June.




Subscribe to our daily 9NEWSLETTER

Download the 9NEWS APP
iTunes: http://on9news.tv/itunes
Google Play: http://on9news.tv/1lWnC5n 


ROKU: add the channel from the ROKU store or by searching for KUSA.

For both Apple TV and Fire TV, search for "9news" to find the free app to add to your account. Another option for Fire TV is to have the app delivered directly to your Fire TV through Amazon.

Before You Leave, Check This Out