Slide 1Outer or Jovian PlanetsUlyssesJupiterJupiter’s MoonsRoche Limit and Tidal FrictionSlide 7The Mills Cross Array from the groundSlide 9Slide 10Jupiter’s “Decametric” EmissionJupiter’s Van Allen Belts - the “Decimetric” EmissionJupiter's AuroraEarth's AuroraSlide 15Slide 16Jupiter's Wind ShearSaturnSaturn’s Moon TitanUranusNeptunePlutoSlide 23CometsSlide 25AsteroidsSlide 272Outer or Jovian Planets•All the Jovian planets are larger than the Terrestrial planets.•All have similar compositions and are similar to the Sun.•Solar composition is mostly Hydrogen, some Helium, etc.•All have low average densities,•All have rings and many satellites.•None have surfaces but only increasingly dense atmospheres and rock and metal cores.3Voyager 1 & 2GalileoPioneer 10 & 11UlyssesSome of the unmanned spacecraft sent to the Outer PlanetsCassini4Jupiter•Largest planet in the Solar System•Rotates more than twice as fast as Earth this causes it to appear slightly flattened at the poles.•Jupiter emits more heat than it receives from the Sun.•The Great Red Spot is a cloud feature that has been observed from Earth for several hundred years! •Jupiter is a strong source of radio waves due to its powerful magnetic field and its interaction with its moon, Io.•Atmosphere is a mix of methane, ammonia, and waterUnmanned missions to Jupiter:• Cassini - Mission to Saturn via Jupiter (2000) • Galileo Orbiter & Probe (1995-2003)• Voyager 1 & 2- Mission to Jupiter (1979), Saturn, Uranus, Neptune, and beyond • Ulysses - (1992- present) Mission to study the Sun via Jupiter • Pioneer 10 & 11(flyby 1973, 1974)5Jupiter’s Moons•The four largest moons of Jupiter (Io, Europa, Ganymede and Callisto) are known as the Galilean satellites after Galileo.•They are roughly the same size as our Moon although the largest one, Ganymede, is larger than the planet Mercury.•Io, the closest moon to Jupiter, is the most volcanically active body in the Solar System! •Europa, the second closest moon from Jupiter, is completely covered in ice. There might be an ocean beneath the ice and conditions suitable for life!Ganymede, Callisto, Io, Europa, the 4 largest of the more than 60 moons orbiting Jupiter Io is volcanic due to tides raised by the gravitational pull of Jupiter and the other moons.Roche Limit and Tidal Friction72047 feet long, 66 antennascourtesy DTM/CIW archivesThe Discovery of Radio Emissions from Jupiter• This discovery was made here in Maryland in Montgomery County, about 20 miles west of the Washington Beltway.• The discovery was made using a radio telescope known as the Mills Cross Array. • The Mills Cross Array was composed of many antennas connected together that worked as one huge antenna.8The Mills Cross Array from the groundThe receivers were housed in an army surplus truck visible in the distance. Undated photo about 1954. Courtesy of the Archives of the Carnegie Institution of Washington9•The Mills Cross Array pointed nearly at the zenith, the Earth’s spin allowed objects to move in and out of view of the antennas.•In early 1955 near the time of transit of the Crab Nebula, Burke and Franklin, two scientists from the Carnegie Institution of Washington noted intermittent bursts of strong radio noise in about 1/3 of their records.Crab Nebula from Burke and Franklin [1955]10•They noticed that the timing of the bursts changed at a sidereal rate, that is at the same rate that the stars appeared to move across the sky so it had to be coming from something in space and not something on the ground.•Further observations showed that the bursts were actually drifting slightly, (could it be a planet?).•Only Jupiter was overhead at the same time as these bursts were detected and drifted at the same rate.•Burke and Franklin announced their discovery on April 6, 1955 at the American Astronomical Society meeting in Princeton, NJ. How did they determine that the radio waves were coming from Jupiter?11Jupiter’s “Decametric” Emission•These radio waves have wavelengths that are a few 10s of meters long, so they are called “decametric”.•The Jovian emission discovered by Burke and Franklin in 1955 is thought to be emitted in a hollow cone pattern near Jupiter’s north and south magnetic poles.•Only when Earth lies in the direction of one of these cones can we receive radio waves.•In 1964, it was found that Jupiter’s moon Io strongly influences the radio emission source. •The Io-related decametric sources are near the field lines passing through Io.RadioEmissionRadioEmissionAuroraIo12Jupiter’s Van Allen Belts - the “Decimetric” Emission•Both Jupiter and Earth are surrounded by zones or belts of high energy particles. These are known as the Van Allen Belts.•In 1959 scientists proposed that the microwave emissions observed from Jupiter could be due to Jupiter’s Van Allen Belt. •Microwaves have wavelengths of about 1/10 of a meter so they are called decimetric waves.•In 1960 scientists confirmed that the microwaves are coming from a region along Jupiter’s equator and a few Jupiter radii away from the planet.A recent image of Jupiter made by observing microwaves of 13 cm wavelength or 2.3 GHz frequency.13Jupiter's Aurora14Earth's AuroraJupiter’s Atmosphere•General convection pattern:–Heat within Jupiter carries gas to the top of the atmosphere–High altitude gas radiates into space, cools and sinksJupiter’s Atmosphere•Coriolis effect turns rising and sinking gases into powerful jet streams (about 300 km/hr) that are seen as cloud beltsJupiter's Wind ShearThe winds in adjacent bands move in opposite directions.18Saturn•Spectacular rings surround the planet. Saturn has at least 33 moons.•The rings are composed of chunks of ice and rock of various sizes most just a few inches across.•One of Saturn’s moons, Titan, has a thick atmosphere and may be covered in ices composed of nitrogen or ethane.•The Cassini mission arrived at Saturn in 2004 and will spend 4 years orbiting the planet. In 2005 the Huygens probe landed on the surface of Titan.Saturn as seen from one of the Voyager spacecraft. A crescent Saturn is impossible to see from Earth.Unmanned missions to Saturn:Cassini/Huygens - (2004-present)Voyager 1&2 - NASA Missions to Jupiter, Saturn (1980,1981), Uranus, Neptune, and beyond Pioneer 11 - (flyby 1979)Infrared image reveals wind shear bands as seen on Jupiter. These bands are below the