Don't look at the sun directly

but there's a rare transit of Venus going on. Those of us in North America can only catch the last part of it, but it's still quite nifty, and there will be another in 2012. They come in pairs with about a century in between; the last one was in 1882.

Venus looks so tiny against the Sun. I wonder what our planet looks like from, say, Mars, during and not during a transit? Maybe someday we'll find out.