International Astronomy Day is a day recognized by amateur and professional astronomers that is set aside for promoting and sharing the love of astronomy with others. To find out where in your area there is an International Astronomy Day event click here (this info is futher down on the link page).
Many clubs organize public events for this day ~ information booths, slide shows, computer presentations, craft tables for children ~ set up in parks, malls, museums or arenas. See ideas on how to from RASC - http://www.rasc.ca/astroday/resources.shtml
The public can get from your club pamphlets and information on astronomy events, clubs, sky observations, how to view the sky and get answers to questions they have. Children can learn about astronomy by making crafts and colouring pictures, answering quizes. Sun spots can be shown to the public using special protective filters on telescopes and people can get a close up view of what a telescope really looks like.