The Jovian Planets

Jupiter.Jupiter

Jupiter

Density: 1.33 g/cc

Spins in less then 10 hours!

made mostly of H and He (just like our Sun)

318 times more massive than the Earth

Jupiter's Structure

Top: clouds eventually thicken to liquids Middle (and mostly): liquid metallic hydrogen

(10 million times the pressure of this room!) Core Rocky, metallic core.

15-30 Earth masses. Probably 20,000 Kelvin (40,000oF)!

Density=1.3g/cc

318 times more massive than Earth.

Made mostly of H and then He

5.2 AU from the Sun

Jupiter contd. The Great Red Spot is a storm that has raged on Jupiter for

at least 300 years! However, it is not permanent.

The clouds vary.....

And sometimes a belt will go missing!

Jupiter's Rings The shape of the rings is determined by small moons, called shepherd moons, Jupiter's strong magnetic field, andof course Jupiter's gravity.

The particles are extremely small- micrometer sized!

The particles in the rings only last for about 1,000 years before falling into Jupiter. But they are continually replenished by impacts

on Jupiter's moons.

Jupiter has at least 63 moons.

Io, the innermost Galilean moon

Io, the innermost Galilean moon*Io is the most volcanically active body in the solar system!* There are no impact craters on Io.*The heating is caused by tides.

Io's structureRocky crust, mantle, and core. Density = 3.5 g/cc

Very thin SO2 atmosphere (volcanoes)

Europa

Slightly enhanced color44x19 miles.

Europa - WEDAlso caught in a tug-of-war between massive Jupiter and

other large moons, Europa has a fairly young surface, with only a few impact craters.

Europa's structureEuropa has a thin (3-20 miles thick) crust made of water-ice. Underneath lies a vast liquid layer of water, perhaps 30 miles thick.But most of the moon is made of rock, with perhaps an iron core. Density = 3.0 g/cc

Europa's structureEuropa has a thin, Oxygen atmosphere created by charged

particles hitting the surface. Comparable to Earth's atmosphere at an altitude of over 100 miles!

Forming ridges: When the ice cracks, liquid/slush pushes up through the crack, forming a ridge.

Ganymede

GanymedeAs we move out from Jupiter, the tidal flexing becomes less, and the surfaces get colder and older. Ganymede is

the largest moon in the solar system and also generates its own magnetic field, just like the Earth!

Ganymede's interiorThin ice crust. Underneath is a thick, water-ice layer (mostly

frozen). Under that is a rocky mantle surrounding an iron core.

Density = 1.9 g/cc

Ganymede has an extremely thin

Oxygen atmosphere created by charged particles hitting the

ice surface.

Though over a billion years old, Ganymede's surface shows signs of extensive upheaval in the past. Probably as the

moon differentiated.

CallistoCallisto's surface is old (~4GYrs) and heavily cratered.

Callisto's structureBeing the furthest moon from Jupiter and under the least

tidal stress, Callisto probably did not have time to differentiate much before it became frozen.

Density = 1.8 g/cc

However, Callisto shows signs of a variable magnetic field, an indication of a subterranean, salty ocean.

Structure changes as they get further from Jupiter.

3.5 g/cc 3.0 g/cc

1.9 g/cc 1.8 g/cc

Jupiter also has lots of smaller, irregular moons. Many are likely

captured asteroids.

3-D

Saturn

Infrared view

Saturn's structure is very similar to Jupiter's.Clouds (thicker, which mutes the color) which thicken to liquidMetallic hydrogen interior Rocky coreDensity = 0.7 less than water!

Solar day = 10 hours 40 minutesThis spin is so fast that Saturn is visibly larger at the equator then the poles.95 times more massive then Earth.

56 known moons

Saturn's Rings.* Are extremely thin: 200,000km across, but typically about 200m thick!* Made of millions of particles- but not very thick!

-1cm to 10m in diameter-mostly ice or ice-covered rocks- all the ring material, compressed into a rock would only be 100km across.

How many rings do you see?

Shepherd Moon

*Titan is larger than Mercury and more massive than Pluto.

*It has an atmosphere. Composed mostly of N

2

like Earth's but 50% thicker than ours.

*- 290F at Titan's surface.*Titan is at the triple point

of ethane/methane

Before Cassini, all we could see were clouds.

Radar images which look through the

clouds to the surface.

What surface features do you see?

Huygens optical picture while parachuting down.

Washed out hydrocarbon gunk.

True color image from the surface. Like Venus, color is determined by the clouds.What are we looking at?The lander detected a 'puff' of methane when it landed.

Artist's recreation of the landing site.

My favorite!

What's this?!

Density = 1.88 g/ccA liquid region within the ice.

Titan.... the other Earth.

• It rains, it pours, it snows, it evaporates.• There are volcanoes and plate tectonics, and few (49

estimated) craters.• There's wind, sand dunes, river beds, and lots of erosion.

• And is there life?

Other moons* Average density of Saturn's moons (except Titan) is ~1.3g/cc: basically they may have rocky cores, but contain substantial amounts of ice. Dione

Mimas

Enceladus

Tethys

Iapetus

Iapetus: a giant walnut

Epimetheus:A captured asteroid?

Hyperion.

Hyperion. Density = 0.6 g/cc

Rhea: Has a thin oxygen and carbon dioxide atmosphere

Discovery of Uranus In 1781 British astronomer William Herschel accidentally discovered Uranus while making star charts visually through a telescope. (He wanted to name it after the King of England: "Georgium Sidus"!).

Discovery of Neptune Adams/Leverrier/Galle 1846 based on mathematical prediction. Credit for discovery is controversial. Discovery of Pluto In 1930 by Clyde Tombaugh after a methodical photographic search.

Uranus

Revolution/Rotation 84 years/17.24R hrs. Atmosphere • Mostly hydrogen• Featureless blue (due to trace amounts of methane) Interior • Rocky core• Highly-compressed water "inner mantle"• Liquid hydrogen/helium "outer mantle”• Gaseous atmosphere of mostly hydrogen:

Both Uranus and Neptune have magnetic fields comparable in strength to Earth’s. Uranus is the planet with greatest tilt. The polar axis lies nearly in the plane of the orbit. The satellites and rings are about in the plane of the equator.

Uranus’ Miranda This smallish satellite (~ 500 km or ~300 mi across) is a strange mixture of surface types. It may have been fragmented by a giant impact and later re-formed. There is a sheer cliff about 20 km (~10 miles) tall at the 5 o’clock position:

Uranus’ Rings Because these dark rings are in Uranus’ equatorial plane, the planet looks like a bull’s eye pattern in this (infrared) image taken by the Hubble Space Telescope:

Neptune Revolution/Rotation 165 years/16.1 hrs Atmosphere Blue-green, but has features, like the Great Dark Spot (discovered by Voyager 2 in 1986; has since disappeared and another formed on the opposite side), and white methane cirrus clouds.

Neptune’s Triton This large satellite has a very low density atmosphere and shows evidence of liquid nitrogen geysers.

Voyager 2 measured a surface temperature of(-395 ˚F) (36 ˚K) on Triton’s odd surface.

Neptune’s Rings These four are so dark that the planet had to be masked off to see them in this 1989 image from Voyager 2. The dusty ring particles may contain carbon and may be due to the disintegration of small satellites that came within the Roche Limit:

THURS The Terrestrial Planets

1) The 4 planets closest to the Sun. 2) They are all solid objects made of rock.3) They all have thin atmospheres (compared to how

much rock they have).4) They have few moons.

The Jovian Planets

1) The 4 planets furthest from the Sun. 2) They are large compared to terrestrial planets3) They are all gaseous planets with thick atmospheres

with small rocky cores.4) They have many moons, and rings!

Dwarf Planets and Small Solar System Bodies Dwarf Planets Pluto We reproduced Tombaugh’s discovery technique at Baker Observatory in June 2004. Which one is Pluto?

Dwarf Planets and Small Solar System Bodies Dwarf Planets Pluto We reproduced Tombaugh’s discovery technique at Baker Observatory in June 2004. Which one is Pluto?

Pluto Physical Properties • Diameter: ~1/5 Earth’s diameter • Mass: < 1% Earth’s mass • Ave. density: 1.8 g/cm3

Revolution/Rotation 249 years/6.4 days Its orbital eccentricity is 0.25. Pluto was actually closer to the Sun than Neptune from 1979 until 1999. Its surface temperature must now be even colder than Neptune's Triton, about –400 ˚F (35 ˚K). Only H, He, and Ne would not freeze!

Four additional small satellites; Nix, Hydra, Kerberos, and Styx have been found orbiting Pluto. The “New Horizons” probe to Pluto was launched January 19, 2006. It achieved a record speed of 36,256 mph, but will take >9 years to get there. On the way past Jupiter it sped up to ~47,000 mph! (Note that the speed of light is ~ 670,000,000 mph!) What is Pluto? Its status has long been controversial due to its small size and mass, and its odd orbit. The discovery of similar objects called “Kuiper-Belt Objects” (KBOs) also orbiting beyond Neptune’s orbit showed the need to re-classify it as a dwarf planet based on the definitions established by the International Astronomical Union on August 24, 2006.

Dwarf Planets in Kuiper belt

Dwarf Planets in asteroid belt