OneAndOneIs2

This morning was a bit of a challenge: A two-hour lesson on the solar system, to follow on from Friday's one hour on the Earth.

Again, it went quite well, and I was fairly happy with it. The main challenge, again, was getting & keeping the kids involved, as you can't easily bring the solar system into the lab...

So although it wasn't really relevant to the lesson, I spent quite a while on the opposition effect - not something the average biochemist is familiar with, but as you may have gathered.. I'm a geek.

Moon dust, when heated by meteor impacts, forms molten droplets, which cool to form pretty good glass beads. Glass beads are retro-reflective: They reflect light back the way it came from, as opposed to mirrors, which reflect them in the opposite direction.

So when the moon is full, and thus in a straight line with the Earth and Sun, retro-reflection kicks in and reflects more light than usual back at us, making the full moon much brighter than it would otherwise be.

The stripes on those yellow safety jackets are also retro-reflective, so I put one on and passed a torch around, and they thought it was really cool the way the strips suddenly seemed to glow when they brought the torch right up to their eyes :o)

After I covered spin, rotation, axial tilt, and some interesting things about all the planets in our solar system, I then handed over to them for the rest of it and had them design their own planet.

Luckily the cast of Star Trek never encountered some of these designs.. cubic and heart-shaped planets were popular, and polka-dot continents featured heavily. One planet had perpetual summer and Christmas every other day, plus bubble-gum flavoured swimming pools. One was a long, round-ended cylinder *cough* with lots of rings around it. And one was inhabited solely by people with the same first name as its creator.

A few people created spherical worlds, but I don't think they'll ever catch on...