Scale: It's All Relative

It's hard to believe, but these are grains of sand, magnified 100-250 times.

Photo copyright: Dr. Gary Greenberg

This is one of the cosmic images depicting newborn stars, taken by the Hubble Space Telescope:

Image courtesy NASA, ESA, and the Hubble SM4 ERO Team

They're gorgeous images, but it's difficult to fully comprehend their size when they're viewed in isolation, without other familiar objects with which to compare them.

How do you explain the size of bacteria?  Or the distance to the sun?

The most effective illustration I've found that depicts the size of things immensely vast and invisibly minute is The Scale of the Universe 2, a flash application created by Cary Huang that is available free online.  With the touch of a scroll bar, learners can zoom from the tiniest quark and neutrino to the outer edge of our observable universe, comparing the relative size of thousands of things in between.

Check it out for yourself here:  http://www.htwins.net/scale2/

Every single time I've played with this application, I've been struck by something new.  The possibilities seem...infinite.