This is the PDF of the presentation I gave at the Nevada County Astronomers in February of 2012. It covers planetary nebulas, observation, science, and current mysteries, and an update on the exploration of Mars sine my presentation in March, 2012.
Here are the Planetary Nebula presentation individual slides as JPG files.
Planetary Nebulas by Mark Albert Graybill is licensed under a Creative Commons Attribution-ShareAlike 3.0 Unported License.
Based on a work at http://saundby.com/astronomy/.