NJIT Physics 320: Astronomy and Astrophysics – Lecture XIII Carsten Denker Physics Department Center for Solar–Terrestrial Research
December 3rd, 2003NJIT Center for Solar-Terrestrial Research The Jovian Worlds The Giant Planets The Jovian Moons Io Europa Ganymede Callisto Ring System
December 3rd, 2003NJIT Center for Solar-Terrestrial Research The Giant Planets Jupiter, Saturn, Uranus, and Neptune = 99.5% of the entire mass of the planetary system Galileo Galilei 1610 Galilean moons and Saturn’s ring (telescope) Pioneer 10/11 and Voyager ½ Galileo and Cassini- Huygens Contribution of degenerate electron pressure Brown dwarfs must have masses less than about 80 M Jupiter
December 3rd, 2003NJIT Center for Solar-Terrestrial Research Jupiter
December 3rd, 2003NJIT Center for Solar-Terrestrial Research Shoemaker-Levy 9
December 3rd, 2003NJIT Center for Solar-Terrestrial Research Atmosphere
December 3rd, 2003NJIT Center for Solar-Terrestrial Research Oblateness Equatorial radius: R e = 71,370 km Polar radius: R p = 66,750 km Oblateness: (R e R p ) / R e = First order correction term in gravitational potential: U / m
December 3rd, 2003NJIT Center for Solar-Terrestrial Research Gravitational Moments J 2 : oblateness and moment of inertia J 4 : mass distribution in outer regions, equatorial bulge, and planets thermal structure
December 3rd, 2003NJIT Center for Solar-Terrestrial Research The Jovian Moons Galilean moon: Io, Europa, Ganymede, and Callisto Rock increase of water-ice crust (volatiles) Formation of moons linked to formation of Jupiter itself Hot Jupiter evaporation of volatiles on the closer moons Tidal interactions volcanism Volcanism similar to geysers (sulfur and sulfur dioxide SO 2 ) Resonance in orbits of Io, Europa, and Ganymede: 1:2:4 ratio of orbital periods Galilean moons are located inside Jupiter’s magnetosphere (210 times r Jupiter v Io = 57 km/s potential differences of up to 600 kV and currents of up to 10 6 A
December 3rd, 2003NJIT Center for Solar-Terrestrial Research Io
December 3rd, 2003NJIT Center for Solar-Terrestrial Research Magnetosphere
December 3rd, 2003NJIT Center for Solar-Terrestrial Research Volcanism on Io
December 3rd, 2003NJIT Center for Solar-Terrestrial Research Europa
December 3rd, 2003NJIT Center for Solar-Terrestrial Research Ganymede
December 3rd, 2003NJIT Center for Solar-Terrestrial Research Callisto
December 3rd, 2003NJIT Center for Solar-Terrestrial Research Internal Structure
December 3rd, 2003NJIT Center for Solar-Terrestrial Research Saturn
December 3rd, 2003NJIT Center for Solar-Terrestrial Research Ring Systems Cassini division Encke gap Thousands of ringlets F ring is very narrow and appears to be braided Ring extend about 5 r Saturn and are very thin ( 10 m, ripples 1 km) Optical depth of ring system between 0.1 and 2 Partially inelastic collisions keep rings thin Ring particles are small, a few centimeters to several meters Rings are highly reflective (albedos in the range from 0.2 to 0.6) Ring systems of Jupiter, Uranus, and Neptune Keplerian shear Shepherd moons Orbital resonance Spiral density waves Poynting-Robertson effect
December 3rd, 2003NJIT Center for Solar-Terrestrial Research
December 3rd, 2003NJIT Center for Solar-Terrestrial Research Atmosphere
December 3rd, 2003NJIT Center for Solar-Terrestrial Research Uranus
December 3rd, 2003NJIT Center for Solar-Terrestrial Research Seasons on Uranus
December 3rd, 2003NJIT Center for Solar-Terrestrial Research Neptune
December 3rd, 2003NJIT Center for Solar-Terrestrial Research Comparison of Internal Structure
December 3rd, 2003NJIT Center for Solar-Terrestrial Research Homework Class Project Continue improving the PPT presentation. Use the abstract from the previous assignment as a starting point for a PowerPoint presentation. The PPT presentation should have between 5 and 10 slides. Bring a print-out of the draft version to the next class as a discussion template for group work Homework is due Wednesday December 10 th, Last chance!