The retrograde motion of the outer planets plays an important role in the history of Astronomy. We present a successful hands-on approach to teach this subject to high school students. In a dark room we have used a sky simulator to project on a white board a series of 24 images of the celestial sphere about 15 days apart, showing Mars and the background stars. The date and time of each image was carefully chosen so that the position of stars was always the same. For each image, a different student used a marker to mark the position of Mars on the board. When lights were turned on the full trajectory could be seen on the board. The same procedure was repeated for Jupiter and Saturn, so that we could discuss the shape and size of each retrograde loop in the context of the heliocentric model.

Biography:

Newton Figueiredo is a professor of physics and astronomy at the Federal University of Itajubá, in Brazil. He has a masters and a PhD degree in astrophysics from the National Institute for Space Research, also in Brazil. His current research interest is focused in science education and technology.