Winter Solstice: Shortest Day of the Year

Today, December 21, is the Winter Solstice in the Northern Hemisphere. The shortest day of the year, today is the official first day of winter. Southern Hemisphere inhabitants are enjoying the beginning of summer and the longest day of their year today. 

Sunrise to sunset on the Winter Solstice. Image Credit & Copyright: Danilo Pivato

Why is today the shortest day of the year? 

As I explained in my Summer Solstice post, we have solstices and equinoxes because of the Earth's tilt on its axis. While the Earth orbits the Sun, one hemisphere is tilted toward the Sun while the other is tilted away. Right now we are tilted away from the Sun in the Northern Hemisphere, and so are in winter. Today is the day that we are tilting most away from the Sun, so it is the shortest day of the year. In Peoria, we have about 9 hours of sunlight, and 15 hours of darkness.

On the Winter Solstice, the Northern Hemisphere is tilted away from the Sun, causing the day to be short and the night long. Image Credit: Wikipedia Commons.

You have probably noticed the Sun rising later and later, and setting earlier and earlier. Did you also notice the sunrise creeping toward the southeast, and sunset creeping toward the southwest? As the Earth orbits the Sun and the axis points away, the Sun rises later and farther south. Now that we have had the shortest day, the sun will rise earlier and move easterly again. On the Spring Equinox, the Sun will rise due east and set due west. 

Our dynamic star. Image Source

I always find the Winter Solstice hopeful. I know that every day after this will be a little longer. We still have several cold months ahead of us, but it is easier to deal with the cold when the Sun is shining. And we are on our way to the Spring Equinox, the official beginning of Spring, on March 20. 

Happy Solstice, and Happy New Year! Enjoy the changing seasons, and the steady increase of sunlight in the Northern Hemisphere. Learn more about what's happening in the night sky in the Dome Planetarium, where we teach about space and science every day. Follow us on Facebook or Twitter for daily updates

Don't miss Star Wars on the Giant Screen at the museum this winter! Plus lots of other fun activities over winter break.