ORBITAL PATTERNS OF JUPITER’S MOONS Doug Jenkins and Tammy Schmidt, The Evergreen State College, Olympia, WA ABSTRACT Jupiter possesses a dynamic satellite system whose mythology dates from the Roman dynasty. In 1610, Galileo’s discovery of moons orbiting Jupiter destroyed the widely accepted geocentric model of the universe. Like Galileo, we also observed moons orbiting Jupiter with the use of binoculars and a telescope from two locations. Empowered with this knowledge, we calculated the mass of Jupiter and its monthly angular movement, which allowed us to determine when Jupiter will return to the same celestial location as it was in May We perceived the motion of the moons to be orbiting the polar regions. Like many fundamentals in science, perceptions are deceiving. REFERENCES Freedman, R.A., and W.J. Kaufmann III Jupiter: Lord of the Planets and The Galilean Satellites of Jupiter. pp In Universe, 6 th ed., W.H. Freeman and Company, New York. Washburn, M., Distant Encounters: The exploration of Jupiter and Saturn, Harcourt Brace Jovanovich, San Diego. Ancient Roman Gods and Goddesses. 14 May Hebe and Ganymede. 14 May mythology.com/hebe_ganymede/ Io and Callisto. 14 May mythology.com/io_callisto/ Jupiter. 11 May Jupiter’s Moons. 14 May /* astronomy/planets/jupiter/moons.shtml ACKNOWLEDGEMENTS Doug would like to thank his wife for her understanding during his all-night stellar observations. We would like to thank E.J. Zita for her constructive comments and direction. We would like to thank the Cal staff for their technological assistance. SUMMARY From Earth’s perspective and due to Jupiter’s angular movement of 1 o per month, the planet will return to its current location in 30 years. Using Kepler’s 3 rd law and Newton’s 2 nd, the mass of Jupiter is 1.8 x kg. The orbital movements of the moons appeared to deviate from Jupiter’s equatorial plane. The optical illusion was created because of Earth’s axial tilt. Ganymede, Europa and Io share predictable orbital patterns in a 1:2:4 ratio. Our null hypothesis is not rejected for the four- moon Jovian system because our study period was too short to get adequate data on Callisto’s orbit. METHODS Observations were conducted on clear nights at two areas from 26 April to 20 May Observer 1, located at 47 o N, 123 o W (Olympia, WA), used 8 x 42 binoculars to record relative positions of the moons to Jupiter. Observer 2, located at 47 o N, 122 o 36’ W (Steilacoom, WA), used a 910 mm Dobsonian telescope with a 10 mm objective. Observers coordinated their viewing times to coincide with each other as well as to track the directional movements of the moons. Each observer drew sketches of the moons’ positions. The observers compared sketches and calculated the orbital period for each moon. The mass of Jupiter was determined using Newton’s 2 nd law and Kepler’s 3 rd law. HYPOTHESIS The purpose of this project is to track the orbital movement and period of each moon by conducting observations over a one-month period. We will compare these observed data with actual data collected from scientific resources in order to predict the location of each moon on successive nights. We will calculate the mass of Jupiter based on the period of its moons. We will calculate the exact celestial return of Jupiter based on its movement throughout the month. We will also build a scale model of the Jovian system for presentation. Our null hypothesis states that Jupiter’s moons have no relative orbital pattern. Mass of Jupiter determined from the orbital periods of its moons (Newton’s 2 nd law and Kepler’s 3 rd law). Alignment of Io, Europa, and Ganymede every 7 days.Predictable orbital periods of Io, Europa and Ganymede. Jupiter’s angular movement of 1 o /month = 30 yr return.