Summary Use spirograph art to model how orbits go through precession (the orbit slowly rotates around the central body). Science content Earth/Space: Sun, Moon, Solar System, Universe (1, 4, 6) Lessons activity is in Forces in Space Materials spirograph set ballpoint pens paper Procedure We usually think of the orbit of a body in space to be fixed, but 'apsidal precession' of orbits (slow rotation of the orbit path) has been observed - see image here: https://en.wikipedia.org/wiki/Apsidal_precession#/media/File:Perihelion… Most planets in the solar system have apsidal precession, but at a very slow rate, so their orbits are almost stationary.https://en.wikipedia.org/wiki/Apsidal_precession Show students orbit precession images. Note that drawings of precession are highly exaggerated - the actual shift on each orbit is very small and only observed after watching an orbiting body for many years. Lunar precession of the Moon around Earth image: https://en.wikipedia.org/wiki/Lunar_precession#/media/File:Moon_apsidal… Also animations of lunar precession at https://en.wikipedia.org/wiki/Lunar_precession A star, called S2, orbiting Sagittarius A* (the black hole at the centre of the Milky Way) has been observed for 27 years to notice precession: https://newatlas.com/space/star-s2-spirograph-orbit-supermassive-black-… Students make art with a spirograph to model the patterns made by precession of orbiting bodies. Grades taught Gr 4 Gr 5 Gr 6
