Heliocentrism Day
— February 17th —
 Once upon a time, humans thought the Sun orbited around the Earth. Every kid should know, by third grade, that this isn't true. And Heliocentrism Day is the perfect day to make sure. Why February 17th? The sun-centered solar system was popularized by two guys, Nicolaus Copernicus (born February 19th, 1473) and Galileo Galilei (born February 15th, 1564). The 17th of February is simply the compromise between these two birthdays. [It's also the day that heliocentrism fan Giordano Bruno was burned at the stake, but that's a different story.]
How to celebrate:
1. Because 2 birthdays are involved, the day begs a birthday cake. But don't give your students empty calories -- make those frosting calories educational. For example, frost a round cake in black, then add thin concentric circles of lighter frosting to trace the orbits of the planets. Get a massive candel for the sun, of course. Do not pass up the learning opportunity of allowing kids to do the decorating. Put a larger diagram of the orbits on the chalkboard. And for extra laughs, put a small piece of cheese to indicate our Moon. Give each kid a coloring page party favor.
2. Print out a solar system coloring page.
3. Print out the planets, cut them out, and then glue them in the proper order onto a larger sheet. Then color them.
4. Bring in spheres of various diameters (beach balls, soccer balls, baseballs, marbles, pin head, etc.) and recreate the motions of planets (see simulation) on the front lawn of your school (or in the sports fields). Have each kid carry the ball that best corresponds to the relative size of the planet (images; consult table of dimensions; more tables) he or she is "assigned." Or they can make their own planets. Give each kid a name tag with the name of the planet they will be carrying. (You, being the supreme entity in the classroom, get to be the Sun.) Then have your kids run around the Sun at the appropriate distance (consult the above web site again, but replace km with cm...making the Pluto kid approximately 9 meters away). If you can plan ahead, lay out their courses with string if you'd like (aerosol line paint is ideal, however). Tell them that the planets all orbit in the same direction, but tell them only after they collide with each other a few times -- they will remember the fact much better. If your students are particularly motivated and coordinated, add to the realism of the activity by having each student spin around while they are orbiting. To liven up an otherwise stiff class, have the carriers of Mercury and Venus exclaim, loudly, "Arggghhh--it burns the flesh!" every orbit or so. If you have a really pale-looking kid in the class, have him/her be the Moon. And please, don't forget to have another teacher or visiting parent videotape or photograph the little planet-holders in action. If you conduct this exercise correctly, your students will never, ever forget the basics of astronomy (a lot of adults don't know what causes the yearly cycle!).
Note: Advanced kids might enjoy a helpful trick for remembering the order of the planets: "My Very Educated Mother Just Showed Us Nine Planets" (Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Pluto).
5. Watch the movie, Galileo: On the Shoulders of Giants (56 minutes). Showing movies to your class is a bit lazy and relies on passive learning, but if you first do something like #2, then you're OK. And, of course, follow with cake (#1).
6. If you live in the District of Columbia, take a field trip to the Library of Congress to see a first-edition copy of Copernicus' On the Revolution of Heavenly Spheres. It's on permanent display on the first floor. Sure, it's just a book, but it's an important book, and emphasizes to young children the value of contributing knowledge (even if it's unpopular knowledge!).
Inquiry:
For more advanced classes, ask them to model the solar system. Don't tell them the Sun is at the center, the order of the planets, or even the number of planets. If you have groups of 10 (nine planets plus the sun), have different groups use different approaches. Give them paper, scissors, and a large open space.
Go to your chalkboard and erase the sun. Ask them what would happen if the sun were removed from the picture. This questions will get them to think about gravity, ideally. Don't just tell them the answer.
Ask your students why the planets are all going around the sun in same direction.
Ask your students how Galileo figured out the Sun spins, too.
Ask your students whether other solar systems behave the same way.
Resources:
Really nifty (yes, that's the technical term) site for displaying the orbits of the planets, among other images.
http://space.jpl.nasa.gov/
Nine Planets Solar System Tour
http://www.nineplanets.org/
Build Your Solar System Game
http://www.bbc.co.uk/science/space/playspace/games/jigsaw/jigsaw.shtml
Have an idea on how to better celebrate this day? Lesson plans, movies, books, links, photograpsh — anything that would appeal to the elementary school kid.
Darwin Day | Heliocentrism Day | Origin of Life Day | Round Earth Day
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