I'm getting email and tweets about a Flash-based interactive tool where you can zoom in and out on the Universe, getting a scale of things from the tiniest fluctuations in the quantum foam of space to the size of the Universe itself. It's done logarithmically, using factors of ten, and does a pretty good job. It's called The Scale of the Universe 2. It takes a few minutes to load, so be patient!
What's funny is, no one who has linked to it seems to have remembered that the two brothers who created it, Cary and Michael Huang, made a very similar tool a little over a year ago (which itself owes its existence to the Eames' venerable "Powers of Ten"). The new one is better in many ways, of course (though I like the music in the old one better; everyone's a critic). There are some nice improvements, like some animation, more objects, things that are relatable to kids (the size of the Minecraft world, for example), and more.
One of the things I like about tools like this are the surprising little bits that you learn if you're really paying attention. For example, at a scale of a few billion kilometers, the only familiar object displayed is the orbit of Neptune. Everything else is a star, and all those stars are red. That's because the only stars that can get that big are massive red supergiants, stars at the ends of their lives that are far heftier than the Sun. If someone notices that oddity and looks it up, hey, they found out something cool!
Which brings me to one minor thing I'd change about this: clickable links. It's not hard to stop at someplace along the scale, see something you don't know ("thou", and "twip"? I had to look those up) and then search for it, but having embedded links to the names would be cool.
I'd also love to see something like this tested in classrooms. I have a pretty decent grasp of scale, so this is fun for me, but I wonder if a kid would get the same feel for it? Right around the one meter mark, where you can see a human, a flower, and an elephant, the scale gets odd. That's because the scale isn't linear, it's logarithmic, changing dramtically quickly with a small movement of the scrollbar. To me, that throws off my internal scaling sense. I wonder if this kind of thing might actually give people a false sense of scale, making very small and very large, distant things seem nearer in size to us? Most people already have a squashed sense of scale -- even logarithmically, the Universe is vastly difficult to appreciate; most of it is empty even over large degrees of factors of ten. It's hard to appreciate even how far away the Moon is, and it's the closest thing in the sky!
Again, I'm just curious. But I do see this as a nice way to get people hooked on cool stuff, and to get them more curious about the Universe around them. And that's fine by me.