Thought of a few more things for older age groups, even high school:
* Gravitational lensing, and how the sun is massive enough to produce and prove this (this was verified by a French astronomer a year or two after Einstein first proposed this)
* Lunar impacts and the reasons for ray craters.
* The reason for the seasons
* Reflectors left on the Moon by Apollo astronauts still being used by astronomers.
Sure, more discussion topics than practical, but gets them thinking about the natural world and how astronomy is not 'rocket science', but mostly just applications of everyday things.
Amateur astronomers and their contribution to real science:
This is something that is little understood, or even contemplated by some amateurs! But, there are a few dedicated souls that make serious contributions to astronomy:
* Occultation chasers: These folks chase down predicted occultations of stars by asteroids and other planetoids. The number of people doing this can range from just one person to dozens. They all simultaneously video this event through their telescopes and submit the information to a central professional observatory in Japan which analysis the data to create a profile of the asteroid which in turn helps determine to greater accuracy the mass of the asteroid and subsequent orbit data corrections that need to be made. This goes a long way to determining if a newly discovered asteroid poses a risk to Earth.
One such group is this one:
http://shadowchaser.com.au/category/...-occultations/
The link below is to the international organisation dealing with occultations. Their home page has a diagram of the profile of asteroids determined by occulatation chasers, and how effective their work can be:
http://occultations.org/
* Supernova monitors: These folks take hundreds of photos of the sky looking for supernovae in distant galaxies. As Supernovae explosions are known to be of very specific types (determined by spectral analysis), and reach very specific magnitudes, the distance of the parent galaxy can be determined with great accuracy.
There are a few collectives in both the Northern Hemisphere and the Southern that work collaboratively to this end.
* Another group is dedicated to finding comets and other minor planets in the solar system. Very dedicated bunch this lot.
* A fourth group follow the major planets, looking for anomalies in their atmospheres and surfaces. The Cassini project around Saturn is one such professional mission that uses amateurs here on Earth to verify certain observations, and vice-versa.
All of the above is possible just because of the sheer number of amateurs looking at the sky far outstripping the number of professionals. Amateur astronomers all making a real contribution to real science.
Alex.