| This is the story of how my day care children and I
created our own Millennial Analemma in the back yard of our childcare
home. The analemma tracks the movement of the sun in the sky thru the year.
Technically, the analemma plots the declination of the sun versus the Equation of Time. As the sun travels higher in the summer and lower in the winter, it also moves a bit ahead of and behind civil time (or "clock time"). We plotted the movement of the sun's shadow for over two years, around the turn of the Millennium, and in the process we learned how the sun moves and what causes the seasons.
I have done astronomy with my day care kids for about 30 years. We have watched partial solar eclipses projected inside a shadow box by a pinhole, and also with my Celestron C-8 and a Mylar solar filter.
The children and Michael are sitting around our backyard analemma, shown by the yellow spots on the shuffleboard court.
|Owen views the sun thru a Mylar solar filter.|| I have taken the kids on astronomy camping trips, where we
photographed Jupiter, Saturn, the Moon and a few constellations. We
also studied the easiest and brightest deep sky objects, such as the
Great Cluster in Hercules and the Orion Nebula.
I have taught children as young as five years old to sketch sunspots using our Celestron C-5+. Creating our own analemma was our biggest project yet. We had a great time.
Many years ago, when I was a child, the analemma was featured on the side of world globes. It looked like a long, skinny figure 8 across the equator. I have read that it was removed because teachers did not know what it was or where it came from.
I have always admired and envied the beautiful analemma photographs featured in Sky and Telescope magazine. Wow! I wanted to do that with my daycare children but could never figure out how.
We provide childcare for ages 2 months up to 11 years, so my work day is busy and chaotic. I felt I would not have time to set up and care for a photography based analemma.
More importantly, however, a multiple exposure of the sun would not be easily visible to the children. I felt that they would not comprehend or appreciate the subtle movements of the sun being captured inside a fixed camera.
I began to think in terms of sundials, gnomons, and the movement of the sun’s shadow. If we regularly mark the position of the suns shadow on the ground at precisely the same time of day, we should see a nice analemma.
I involved the day care children from the start. Our first job was to devise a way to cast a circular shadow on our cement shuffle board court. This shadow would be our "analemma spot". Enough spots would outline the analemma.
| We settled on a large screw eye mounted onto a sturdy wooden
fence. The “ears”
visible on the screw eye are made of electrician’s tape. Due to
diffraction effects, the shadow at winter
solstice was so fuzzy as to be difficult to localize. The tape
Every week or two, we would go out at mid-day and mark an analemma spot on the pavement. The sun moves one full diameter in only 2 minutes, so the correct time is critical. At first we used a digital watch adjusted to a time signal on our tiny shortwave radio.
Eventually we purchased a radio controlled clock. It was inexpensive, battery operated, and very convenient.
We set an alarm to remind us to go outside, 11:55 AM during the months of Standard time, 12:55 PM when Daylight Savings time was in effect. When the alarm sounded, the younger children would scream “Analemma! Analemma!” and run into the back yard. The older children would gather up our “atomic” clock, the waterproof marker, and the yellow paint and brush.
The kids loved watching the sun’s shadow, and I loved seeing their amazement at the sun’s simple movement. Over and over the pre-schoolers would yell “It’s moving!” “Look at it move!” As noon (or 1:00 PM) approached the children often chanted a countdown. The analemma creation process was hugely popular.
I began to call it our “Millennial Analemma” after we successfully recorded a spot on the date 1/1/1.
Gnomon in the foreground with analemma and kids.
Erin and Charlotte paint an analemma spot.
| Each sun circle was quickly traced with the permanent
marker and then later filled in with yellow paint. That sounds easy,
but we had several problems. The site was often wet or covered with
snow and ice. We tried a variety markers which did not work under
water, including Sharpie® brand markers, pencil, grease pencil,
felt-tip marker, and china marker. We had the most success with Rub a
Dub® laundry markers.
We filled in each circle with yellow paint to make the marks look like a small sun. At first we used water-based acrylic paint, but that did not survive the Minnesota winter. We switched to an oil-based paint, and that was more permanent.
Shoveling the snow was hard work and fun. The children loved making the analemma, and they were more than willing to help with the work.
Overall, the project took about two years. At the end we had our own Millennial Analemma, and all of the children knew a great deal more about the movement of the sun in the sky. The equation of time was too difficult a concept for all but the oldest children, age 9 to 11. However, the younger children, from age 4 up, did grasp several fundamental concepts:
| We also discussed the related ideas that the summer sun
travels a longer path across the sky, and that it is “up” for more
hours. The children came to see that the longer hours of sunlight
coupled with the higher angle in the sky is what makes summer. This
understanding is a significant accomplishment.
We followed up with demonstrations using a globe, showing the how the movement of the tilted earth around the sun creates the pattern observed in our back yard.
Because of the analemma project, our day care kids understand the seasons better than many high school or college astronomy students. At the beginning of our project, no one in the day care, either parents or children, had ever heard of the analemma.
We have a question for the readers of Sky & Telescope. Have any of you seen an analemma plotted out on the ground in the same manner as our Millennial Analemma? We wonder if ours is the first done at a child care or school.
Charlotte and Soren clear snow for marking analemma spot.