The Outer Planets
Jovian Planet Properties
Jovian Planet Properties Compared to the terrestrial planets, the Jovians: are much larger & more massive are composed mostly of Hydrogen, Helium, & Hydrogen compounds have no solid surfaces rotate more quickly have slightly squashed shapes have many moons have ring systems
Inside the Jovian Planets All Jovian cores appear to be similar. made of rock, metal, and Hydrogen compounds 10 x the mass of Earth Uranus & Neptune captured less gas from the Solar nebula. accretion of planetesimals took longer not much time for gas capture before nebula was cleared out by Solar wind Only Jupiter and Saturn have high enough pressure for H & He to exist in liquid and metallic states.
Jovian Storms We also see high pressure storms analogous to hurricanes, but they rotate in the opposite direction Jupiter the Great Red Spot we are not sure why it is red Neptune the Great Dark Spot
The Jovian Atmospheres The temperature profile of each planet determines the color of its appearance. Cloud layers form where a particular gas condenses. Saturn has the same cloud layers as Jupiter. they form deeper since Saturn is colder overall they are spread farther apart since Saturn has lower gravity Uranus & Neptune cold enough to form methane clouds
Jovian Magnetospheres Saturn, Uranus, & Neptune have smaller & weaker magnetospheres. fraction of electrically conducting material in interiors is smaller Solar wind is weaker farther out, or else their magnetospheres would be even smaller we can not explain the magnetic field tilts of Uranus & Neptune.
Jovian Planets have Numerous Moons We can divide them into three groups: small moons medium moons 300 to 1,500 km in diameter large moons less than 300 km across they are not spherical probably captured asteroids greater than 1,500 km in diameter both groups formed like planets out of the mini-solar nebulae
Comparing Jovian Ring Systems Compared to Saturn, the other ring systems: have fewer particles are smaller in extent have darker particles Why this is so, we are not sure. Other unsolved mysteries: Uranus rings are eccentric and slightly tilted from its equatorial plane. Neptune has partial rings.
Saturn s spectacular rings are composed of fragments of ice and ice-coated rock
Moons Pandora and Prometheus act as shepherd moons and keep the F ring to a band about 100km wide because of gravitational effects.
Dust spokes in Saturn s rings
A system of rings and satellites revolves around Uranus Uranus sports a hazy atmosphere with few clouds
Uranus tilt gives it very exaggerated seasons
Pluto was discovered in 1930 by Clyde Tombaugh by comparing photographs taken a few days apart.
Pluto and its moon, Charon, are about the same size
Origin of the Comets The nebular theory predicted the existence of the Kuiper belt 40 years before it was discovered! The leftover icy planetesimals are the present-day comets. Those which were located between the Jovian planets, if not captured, were gravitationally flung in all directions into the Oort cloud. Those beyond Neptune s orbit remained in the ecliptic plane in what we call the Kuiper belt.
The Kuiper Belt of comets spreads from Neptune out 500 AU from the Sun
Kuiper Belt Object 1993SC - these images were taken 4.6 hours apart
Comet Kohoutek and Comet West
Comets lack tails until they enter the inner solar system
Comets often have two tails: a thin ION tail and a curving DUST tail
Anatomy of a comet
15 km long by 8 km wide Comet Halley nucleus
Comets don t last forever Fragmentation of Comet West shortly after passing near the Sun in 1976 (sequence of photos is from March 8 to March 24)
Dave Jewitt, Jan Fernandez, and Scott Shepard
Comet orbits are altered by gravitational interactions with planets
Small rocky debris peppers the meteors falling stars shooting stars bolides fireballs each are caused by small rocks colliding with Earth s atmosphere and heating up due to friction with the air solar system
Shower Primary Meteor Showers Date of maximum intensity Typical hourly rate Constellation Quadrantids January 3 40 Bootes Lyrids April 22 15 Lyra Eta Aquarids May4 20 Aquarius Delta Aquarids July30 20 Aquarius Perseids August 12 80 Perseus Orionids October 21 20 Orion Taurids November 4 15 Taurus Leonids November 16 15 Leo Major Geminids December 13 50 Gemini Ursids December 22 15 Ursa Minor
The Titius-Bode Law: A series of numbers add 4 divide by ten measured value Planet. 0 4 0.4 0.39 Mercury 3 7 0.7 0.72 Venus 6 10 1.0 1.0 Earth 12 16 1.6 1.52 Mars 24 28 2.8 2.8 Ceres 48 52 5.2 5.2 Jupiter 97 100 10.0 9.54 Saturn 192 196 19.6 19.19 Uranus 384 388 38.8 39.44 Pluto Neptune???
Homework #6 Use Bode s rule to calculate how far the eleventh planet (lets call it planet X) should be from the Sun in our solar system. How long is the year on planet X?