Happy Solstice!

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. This is my third Winter Solstice in a row, because I was in Chile (as part of the Astronomy in Chile Educator Ambassador Program) for the June solstice. While people at home were enjoying the longest day of the year, I experienced the shortest day of the year in the Southern Hemisphere!

A scene from my Chilean solstice in June. Because they have a very temperate climate, there were flowers growing and green grass on their winter solstice!

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 Sun, today, on the Winter Solstice. Image Credit: Solar Dynamics Observatory

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. 

There is something for everyone to do at the Peoria Riverfront Museum over the coming weeks. Exhibitions, Holiday Boredom Busters, Planetarium shows, and Star Wars: The Force Awakens in our Giant Screen Theater.