At 8:30 p.m. tonight, it’s Earth Hour. Turn off your lights, and get off the computer!

Critics wonder, what’s the point of turning lights off for an hour on one day when we abuse the Earth for the other 8,736 hours in the year? But I truly believe that the buzz around Earth Hour does a great job of making more people more aware that we all have the power to make a difference.

For instance, 400 cities were involved in 2008. Last year, there were 4,000 cities. I haven’t seen the numbers yet for this year, but with something like 170 countries involved, there have to be even more cities taking part.

And the difference is pretty dramatic, as you see in the before and after photos.

Of course, don’t just turn off your lights (computers, TVs, radios, etc.). Reduce. Reuse. Recycle. Car pool. Take public transit. Walk. Bicycle. Shop locally. Bring reusable bags when you shop. Every little bit counts!

UPDATE NEXT DAY: There were 126 countries, more than 4,000 cities and towns, and hundreds of millions of people involved. For Ontario, the drop in electricity use was about 4%, or enough to power a suburb of Toronto. Here’s a gallery of this year’s photos. I just love the before and after pics (and these — click on the images to see the fade to the “after” shot).