Download
planetary rings n.
Skip this Video
Loading SlideShow in 5 Seconds..
Planetary Rings PowerPoint Presentation
Download Presentation
Planetary Rings

Planetary Rings

139 Views Download Presentation
Download Presentation

Planetary Rings

- - - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript

  1. Planetary Rings

  2. Rings are swarms of orbiting particles • Orbits have to be very circular • Elliptical orbits will result in collisions, destroying the ring

  3. Rings Have to be Very Flat • Inclined orbits will result in collisions and destruction of the ring

  4. Rings have to be Equatorial • Tilted orbits precess; the plane of the orbit rotates due to the planet’s equatorial bulge, other satellites, and the Sun’s gravity

  5. A tilted ring won’t stay flat very long • Particle orbits will precess at different rates • Collisions will soon destroy the ring

  6. Rings, Gaps, and Resonances • When two objects return to the same relative positions regularly, they are said to be in resonance • Some resonances are stable. Mercury’s 3:2 resonance between its rotation and its orbit is an example. • Pluto’s period is 3/2 that of Neptune’s. This resonance keeps the two planets from ever colliding even though their orbits cross.

  7. Rings, Gaps, and Resonances • Some resonances create gaps. There are no asteroids with one-half Jupiter’s period because repeated pulls by Jupiter eventually would change the asteroid’s orbit. • Gaps in Saturn’s rings are due to resonances with Saturn’s satellites.

  8. Shepherd Moons Shepherd Moons help maintain the sharp edges of rings

  9. A Shepherd Moon Outside a Ring Tends to Drag Stray Particles Back, Causing Them to Fall Back Into the Ring

  10. Outer Shepherd Moon

  11. A Shepherd Moon Inside a Ring Tends to Speed Stray Particles Up, Causing Them to Rise Back Into the Ring

  12. Inner Shepherd Moon

  13. Rings Are Probably Short-Lived • Gravity of the Sun and planet’s satellites constantly disturbs orbits of particles • Collisions probably happen frequently • Particles should drift out of the ring • Rings around outer planets have probably come and gone repeatedly during history of Solar System