Rocket Science for the Rest of Us

The lesson is here: http://www2.jpl.nasa.gov/basics/bsf6-3.php

Another straightforward lesson about the spectrum, how it's categorized and why its useful to study it.  In short, certain elements can absorb specific frequencies, so by getting a spectral reading, we can determine the composition of the planet.  It's also an important science for asteroid mining.  (This is an old article, but explains why.  This month's Popular Mechanics has a terrific article on asteroid mining.  I'll review it later.)