Introduction to the Solar System

Largest organics seen in Halley are polymers of H2CO -- like sugars
However, carbonaceous chondrites, which are probably a lot like the dirt part of the dirty snowballs of comets, have lots of organics that have been analyzed on Earth
3% of the organics are amino acids
Amino acids are also formed in interstellar clouds (proto-solar systems)
Comets may or may not have amino acids
Polycyclic aromatic hydrocarbons (complex organics, like benzene) are also found in meteorites
Probably exist in comets, but have not been detected
Recall that Halley is 30% organics

10X bigger than Earth
1000 Earths could fit into Jupiter
Jupiter is almost all H2, with some He, and trace amounts of S, C compounds of H. The clouds we see are water, water ice, ammonia hydrosulfide ice, and ammonia ice. Tiny part of Jupiter's overall makeup. Jupiter is mostly made of what was in the original solar nebula
The bands we see are the clouds, with the color produced by trace amounts of sulfur and hydrocarbons
They are stretched into bands because Jupiter rotates so fast 10 hour day
Jupiter rotates so fast that it is a flattened sphere -- noticeable in a telescope
Jupiter has no surface -- below the clouds is just hydrogen gas
But if you go far enough down, there is a rocky, icy core, about 20 times Earth size.
Dark bands are called belts
Light bands are called zones
Dark areas are where we are looking further into the planet -- clouds are lower.
There's a huge storm on Jupiter -- Great Red Spot 3X size of Earth
First seen by Cassini using a telescope in 1665 -- so it's been there a while
It is like a hurricane and revolves counterclockwise
Winds can get 400 mph
When you look at Jupiter in a telescope, you can often see the 4 Galilean moons, named after Galileo who first saw them

Out where Jupiter is now, a rocky, icy body accreted within the H2 and He solar nebula, just like the Earth, Venus, Mars, and Mercury. But when it grew to about 15X Earth size, it had enough gravity to pull in the gas, too, and this is what most of Jupiter is made of.
But Jupiter is still generating heat, left over from the phase of contraction that formed it
In fact, Jupiter produces more energy than it receives from the sun
This is very unlike Earth, where the heat within (due to radioactivity) supplies only 0.005% of the energy that the Earth receives from the sun
The energy that drives the weather and clouds on Earth and Venus and Mars is the sun. Not so on Jupiter -- the weather, clouds and winds are driven by heat energy coming up from inside.
But the energy form Jupiter doesn't come from nuclear reactions, like the sun.
It never got big enough to squeeze the H2 atoms in the center, and become a star
If it had become 80 times bigger, it would have ignited as a star

Jupiter has a very powerful magnetic field, 20 X Earth's.
The powerful magnetic field traps particles from the sun and those given off by its moons
Causes immense aurora, and strong radio waves
Electrons moving in a magnetic field create radio waves by a process called synchrotron emission. This is how Jupiter's magnetic field was first detected
Charged particles are caught in a huge doughnut around Jupiter, similar to but vastly larger than the ones around Earth, called the Van Allen belts
There is so much radiation here that spacecraft electronics can be damaged, so they have to pass quickly through this region, called the magnetosphere

Below the clouds is hydrogen and helium gas
But the pressure gets so high (millions of time Earth atmospheric pressure) that below a certain depth, hydrogen becomes a liquid
Below that, the hydrogen gets so squeezed that the electrons break off, and float around with the hydrogen nuclei, making it a metal
Metallic hydrogen was first discovered in the lab only a few months ago by using a huge anvil to create very high pressures
Rock/icy core at the bottom
Jupiter also has a very thin ring system, made of dark, sooty particles (probably rock and carbon). This was first seen when Voyager went by in 1979. Was seen by accident when it was back lit by the sun

Most distinctive feature is its ring system, 40,000 miles wide, but only 1 mile thick
Galileo's telescope wasn't so good -- he thought it was 3 planets together
But in 1655, Christian Huygens saw the rings for what they were
Cassini noticed the large gap in the rings, which we can see in telescopes easily. It's called the Cassini division
The rings are made of water ice, 30 m size chunks further out, 3 m size chunks closer in
Saturn is about 3/4 size of Jupiter, but has a much smaller core
It isn't as colorful, maybe not as many trace elements condensed into clouds. But there are also storms
HST movie of storm on Saturn
Saturn's day is about the same as Jupiter's -- about 10 hours, a bit slower than Jupiter
There are rings around Saturn because tidal forces keep the ring particles from clumping into moons. There are inside the Roche limit
But from gravitational theory, we expect that rings should not be stable -- they should drift off into space
Voyager discovered shepherd moons -- moons that keep the rings compressed
There are thousands of individual strands to the rings, and we can even see spokes swirling in them from the voyager images
The shepherd moons also clear out gaps in the rings. We can see the big ones from Earth, but there are many tiny gaps that can only be seen by spacecraft
Rings are small bits of ice blasted off the larger moons orbiting outside the rings. Tidal forces keep the rings from accreting into moons

VIDEO: TO BOLDLY GO, NOVA (First half)

6/20/96