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A Solar System within

A Solar System within. a Solar System. Physical Properties. Earth Jupiter Mass 1 318 kg 5.97x10 24 1.899x10 27. Physical Properties. Earth Jupiter Radius 1 11.2 equatorial 6378 71,492 polar 6357 66,854

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A Solar System within

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  1. A Solar System within a Solar System

  2. Physical Properties Earth Jupiter • Mass 1 318 kg 5.97x1024 1.899x1027

  3. Physical Properties Earth Jupiter • Radius 1 11.2 equatorial 6378 71,492 polar 6357 66,854 • Oblateness 0.003 0.065 Equatorial radius – polar radius Equatorial radius

  4. Physical Properties • Density 100% 24.0% kg/m3 5515 1326 • Jupiter’s density is only 1.3 x water’s density.

  5. A Truly Wicked Magnetic Field • Jupiter’s magnetic field is the strongest and largest, next to the sun’s. • It’s so large that it interacts with the Jovian moons (electrically), and even stretches out as far as Saturn.

  6. Field is 14Xstronger than earth’s field at the equator… 4.2 Gauss vs. 0.3 Gauss.

  7. How is a strong field compatible with the low density? • Chemical composition • 90% H by volume (75% by mass) • 10% He by volume (25% by mass) • <1% of methane (CH4), ammonia (NH3), and ammonium hydrosulfide (bright colors)

  8. What is the conductor? • At the high pressures found in Jupiter’s interior, hydrogen gas becomes a liquid metal, and therefore electrically conductive. • At least 1.4 Megabars of pressure are required.

  9. Metallic Hydrogen • Metallic hydrogen has been produced in a lab by shock compressing gaseous H. • Here’s a website from the researchers that first made metallic H if you’d like to read further: https://www.llnl.gov/str/Nellis.html

  10. Orbit • Average distance from the sun: 778.6 million km (5.2 A.U.) • Perihelion: 740.5 million km • Aphelion: 816.6 million km • Orbit Eccentricity: 0.049

  11. Orbit (2) • Orbital Period: 11.86 years • Orbital Velocity: 13.1 km/s • Inclination of orbit to ecliptic: 1.3o • We have modern evidence that Jupiter’s been the target of collisions with other bodies.

  12. Rotation • Rotational Period: 9.93 hours • Axis is tilted 3.1o to the orbit. • How was this measured? (3 ways) • Homework question: A point on earth’s equator rotates with an eastward velocity of about 1670 km/hour (464 m/s). Calculate the eastward velocity of a point on Jupiter’s equator.

  13. Rotation’s Effect on Jupiter’s Weather • No surface N-S convective cells • Belts (upwelling gas, darker stripes)** • Zones (sinking gas, lighter stripes)** • Gas flow is in opposite directions • Differential rotation • Faster at equator (9h 50m) • Slower at poles (9h 56m) **new result from Cassini spacecraft

  14. Unanswered Questions • Turbulence and atmospheric friction should have bled off much of Jupiter’s rotational energy, by converting it to kinetic energy in the atmosphere and raising the atmosphere’s temperature. • Yet Jupiter still rotates very quickly, and the upper atmosphere is cold. Why?

  15. More Rotational Effects • Great Red Spot • first observed in 1664 by Robert Hooke • size, color, shape changes regularly • predatory! • Great Red Spot Junior • White Ovals

  16. Great Red Spot movie http://antwrp.gsfc.nasa.gov/apod/ap001123.html

  17. All the Gas Giants have rings! • Jupiter has a set of 4 rings • much less substantial than Saturn’s rings • only visible by backlighting • Discovered by Voyager 1 • Formed from dust blasted off 4 small inner moons by impacts (Amalthea, Andrastea, Metis, Thebe)

  18. The backlit rings are totally inside Io’s orbit.

  19. The Satellites • 4 Galilean Moons: Io, Europa, Ganymede, Callisto • 44 Named asteroidal moons • 15 as-yet-unnamed asteroidal moons

  20. The orbits of the moons are in resonance with one another. All 4 moons orbit in synchronous rotation.

  21. Moon Data Io Europa Ganymede Callisto Radius 1821 1561 2631 2410 (km) Density 3530 3010 1940 1830 (kg/m3) Orbit 5.9 9.4 15.0 26.3 Radius (Rj)

  22. Io • More than 80 erupting volcanoes. • Surface is entirely sulfur and sulfur compounds. • Volcanoes spew sulfur dioxide, which “rains” back onto the surface. • Electrically conductive sulfur and oxygen ions escape Io’s gravity, and orbit Jupiter in a torus.

  23. Tvashtar Eruption Movie • Planetary Society

  24. The Io Plasma Torus rotates along withJupiter’s magnetic field, once every 10 hours. Jupiter’s magnetic field is not aligned perfectly with its spin axis, so the torus has a “wobble”.

  25. A movie of the Io Plasma Torus http://haydenplanetarium.org/resources/ava/page/index.php?file=P0404juptorus An electrical current flows from Jupiter toIo and back again: 2 trillion watts of power. This current flows through the Flux Tube.

  26. When Io is properly aligned, this current emits radio signals at around 20.1 MHz. (Radio Jove Project)

  27. Why hasn’t Io cooled off? • Io is about the same size and mass as the earth’s moon. • Our moon shows no current volcanic activity. • Why isn’t Io in the same state?

  28. Europa • Salty ice crust – the flattest surface of any planet or moon in the solar system • Subsurface liquid or slushy ocean? • Linea or tectonic cracks • Few craters

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