1 / 28

The Moons of the Gas Giants

The Moons of the Gas Giants. Astronomy 311 Professor Lee Carkner Lecture 20. The Group of Seven. There are seven large (diameter >2000 km) satellites in the solar system Each is a distinct world of its own. Jupiter’s Lovers. Io, Europa and Callisto were Jupiter’s lovers in Greek mythology

prince
Download Presentation

The Moons of the Gas Giants

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. The Moons of the Gas Giants Astronomy 311 Professor Lee Carkner Lecture 20

  2. The Group of Seven • There are seven large (diameter >2000 km) satellites in the solar system • Each is a distinct world of its own

  3. Jupiter’s Lovers • Io, Europa and Callisto were Jupiter’s lovers in Greek mythology • Saturn was the king of the Titans

  4. The Galilean Moons • Discovered by Galileo in 1610 • Studied by Voyager 1 and 2, HST and Galileo (the spacecraft)

  5. Orbits of the Galilean Moons • All are tidally locked to Jupiter in a 1-to-1 ratio • 1 • The periods of the orbits of the 3 inner moons are in a 1:2:4 ratio

  6. Formation of the Galilean Moons • The inner parts of the nebula were hotter than the outer • The inner 3 satellites experienced tidal heating and differentiated into a rocky core and an icy crust

  7. The Interiors of the Galilean Moons

  8. Galileo Visits the Galilean Moons • The Galileo spacecraft arrived at Jupiter in 1995 and has been studying the moons from Jupiter orbit ever since

  9. Galileo at Io

  10. Surfaces of the Galilean Moons

  11. Io • Io is the most volcanically active world in the solar system • These changing forces squeeze and flex Io producing heat • The interior heat has also produced a differentiated interior

  12. Volcanism on Io • Io has no impact craters • Volcanoes produce plumes of material that extend up to 280 km above the surface • Volcanoes can be very long lived

  13. Io’s Plasma Torus • Io’s volcanoes put lots of ions into its orbit • The ions are effected by Jupiter’s magnetic field producing a plasma torus

  14. Europa • Europa’s surface is covered with a layer of ice • Water flows up to the top continually resurfacing Europa • Tidal flex may also crack the surface

  15. Evidence for Warm Oceans on Europa • Europa has ice rafts where the surface has been broken up and reassembled • Europa also has smooth areas where water has flowed up and re-frozen • Galileo magnetometer measurements indicate that Europa has a variable magnetic field

  16. Models for the Interior of Europa

  17. Ganymede • Ganymede is the largest moon in the solar system • Ganymede should have little tidal heating due to its distance from Jupiter • Ganymede must have had more geological activity in the past

  18. The Surface of Ganymede • Ganymede shows 2 types of surface features • Old dark terrain • New bright terrain

  19. Callisto • Callisto is the most distant Galilean moon from Jupiter • It has experienced the least tidal heating • Callisto shows few signs of interior or surface activity • Large impact basin Valhalla

  20. Titan • The second largest moon in the solar system • Only moon with an atmosphere • Why does Titan have an atmosphere?

  21. Titan’s Atmosphere • Titan has a thicker atmosphere than the Earth • Titan’s atmosphere may have originally been composed of ammonia (NH3) and methane (CH4) • 90% of the atmosphere is N2

  22. Chemicals in Titan’s Atmosphere • Titan’s atmosphere also contains hydrocarbons (composed of H and C) and polymers (long chains of H, N and C) • Titan may have the necessary organic material to form the building blocks of life

  23. Triton • Triton is in a decaying, highly inclined (23 degrees), retrograde orbit • Triton shows evidence of geologic activity • When Triton was first captured it was probably in a highly eccentric orbit which resulted in tidal heating

  24. Triton’s Atmosphere • Triton has a very thin nitrogen atmosphere (1.6 X 10-5 atmospheres of pressure) • A little bit of nitrogen evaporates to produce the atmosphere

  25. Summary • The six large moons of the gas giants resemble the terrestrial planets of the inner solar system • They can have volcanoes, atmospheres, and evidence of resurfacing • In general they are cold and have rocky interiors and icy exteriors • Some produce internal energy through tidal heating • Europa and Titan may possibly have the conditions for life to exist

  26. Summary: Io and Europa • Io • Strong tidal heating produces massive volcanism • Volcanism produces powerful outgassed plumes, sulfurous surface and plasma torus of ions • Europa • Icy surface shows evidence for water flowing up from interior • May have a warm subsurface ocean due to tidal heating

  27. Summary: Ganymede and Callisto • Ganymede • Shows both old dark terrain and bright new terrain • Must have had more internal heat to drive geologic activity in the past • Callisto • No tidal heating results in no differentiation • Fairly uniform mixture of icy and rock with many craters

  28. Summary: Titan and Triton • Titan • Large size and low temperatures results in an thick atmosphere • Atmosphere composed of nitrogen, methane, hydrocarbons and polymers • Triton • Has a decaying, inclined retrograde orbit • Thin atmosphere and surface activity

More Related