Shapes of Free Fall

The shapes of the orbits of many planets and comets orbiting their mother-ship stars are well known to be circles or ellipses (an idea that was explained by Isaac Newton). But we now understand that, depending on the history and the energy of the orbiting system, other geometric shapes are possible and indeed frequently observed. This talk will explore how simple changes to the circumstances can make dramatic differences to the shapes of the orbits, all of which belong to a special family ...