Took a group of happy kids and their Mom on a short ride to their car today. As I often do with children, I asked them what their favorite subjects are in school. I was charged to learn they all liked science and math! Lucky for us we would be passing one of my favorite spots on the Mall where the solar system is proportionally laid out in a one to ten billion scale on oval metal signs. At each planet, there is information about how many moons, temperature, day and year length, chemical composition, distance from the sun, and many other interesting factoids.

http://voyagesolarsystem.org/

"one to 10-billion scale model of our Solar System—spanning 2,000 feet from the National Air and Space Museum to the Smithsonian Castle. The Sun and its system of planets—our Solar System—is portrayed at one 10-billionth actual size, and contained on 13 stanchions."

The first stanchions or oval metal sign starts with Voyager and I tell them it has actually gone out of the solar system, waving my hand up and out. Then there is poor Pluto. And I always tell the same joke. "Pluto has been demoted as a planet. People who have been laid off say they have been Pluto-ed."

And I keep pedaling past the Arts and Industries Museum undergoing asbestos removal with a stimulus grant, point out Neptune with its 8 moons. And keep pedaling past the Hirschorn Museum of Modern Art and entrance of the Air and Space Museum and see the local planets, Mars, Earth, Venus and Mercury and the sun we spin around. I try to instill a little reverence for the uniqueness of our little planet.

"And look how perfect this Earth is for life: water can exist in all three forms- solid ice, liquid water and gaseous vapor," pointing to the sky. " So life has a chance to evolve."