From time immemorial, the summer solstice has been celebrated by people and cultures across the globe. The ancients depended on the yearly pattern of day-light hours to set their calendars and determine the best time to plant and harvest crops. The summer solstice, which typically falls on June 21st, is the longest day of the year and after this date, the days become progressively shorter as we head into fall.
The movement of the celestial spheres may seem rather separate from our busy modern lives. But if you think about it, everything from the food we eat to the way we plan our day is intimately connected to the time and seasons, which are affected by the motion and attitude of the Earth as it moves around the sun!
1. Stand a stick upright in a box of sand or dirt.
2. In a darkened room, use a flashlight to shine a beam of light over the stick. See how you can make the stick’s shadow longer or shorter by changing the height of the flashlight. Make three observations; one with the flashlight directly over the top of the stick so that there is no shadow, one casting a small shadow only an inch or two long, and one with a shadow about as long as your stick.
(This is similar to what is happening to the Earth as it moves around the sun over the course of the year. Although the sun doesn’t move like our flashlight, the Earth does and that affects how high or low the sun appears in the sky and how long shadows are. During the summer months, the northern half of the planet where we live is turned toward the sun. On June 21st, we are facing the sun directly so the sun appears straight up above our heads. The highest point the sun reaches in the sky in a single day is what we call noon, or 12:00pm. The higher up the sun is in the sky at noon, the longer the daylight hours are between the time when the sun rises and sets.)
3. At noon, take your stick and box outside and see where the stick’s shadow is now. Try measuring the shadow. Which of your flashlight observations is most similar to length of the shadow cast by the sun?
*If you’re good with math you can use the Windows calculator on your computer to find out the angle of the sun in the sky. Here’s how: Go to the Start Menu on your computer and select Calculator. Go to View and select Scientific. Divide the length of the shadow cast by the sun by the height of the stick. Make sure the little bubble that says “degrees” on the calculator is selected. Select the button that says “Inv”. Now select the button that says “tan−1“. The number that comes up is the angle in degrees. If you get a zero, that means that the angle of the sun is zero and the sun is directly over head.
Now that you’ve discovered the science of the solstice, it’s time to get out and celebrate it in the best way possible by signing up for Run Wild in the Woods on Saturday June 22nd. This event is a 10k run/5k walk through beautifully rugged, unglaciated terrain at our Black Earth Campus. For details and to register online, see the link above!
See you at Black Earth!