1. Life on Mars? It has been proven there is water ice on Mars.
Probably below the surface today but a large ocean in the past.
Water  life
but is it extinct, dormant or alive?

2. Methane & Water!
Data obtained by the Mars Express probe show that water vapor and methane gas are concentrated in the same regions of the Martian atmosphere.
Methane only lasts about 100 years (UV light destroys it)
Must be recently made!
Life (micro-organisms) or volcanoes?
If microbes are making methane in the Martian atmosphere as part of their living process, they would rely on water. 2

3. Life on Mars? Direct search by space probes
1976 Viking probes - inconclusive
2003 Beagle II – crashed on landing

4. Beagle II crash images

5. Not Beagle II crash images

6. Life in the Terrestrial Planet Region?X
MERCURY
MOON
VENUS
MARS
Terrible Extremes of Temperature, No Atmosphere, UV, Cosmic Rays, Little or No Volatiles, No Liquids X
Terrible Extremes of Temperature, No Atmosphere, UV, Cosmic Rays, Little or No Volatiles, No Liquids X
Very High Temperatures, No or Little Water
Young Surface  No Fossil Record ?
Evidence for Liquid Water in Past
Possible Environments for Life to Survive?
Volatiles and Water Present Now

7. The JOVIAN PLANETS

8. They formed beyond the frost line to form large, icy planetesimals which were massive enough to…
Capture H/He far from Sun to form gaseous planets.
Each Jovian planet formed its own “miniature” solar nebula.
Moons formed out of these disks.

9. All the Jovian planets are larger than the Terrestrial planets.
All have similar compositions and are similar to the Sun.
Solar composition is mostly Hydrogen, some Helium, etc.
All have low average densities,
All have rings and many satellites.
Remember: J-SUN

10. Interiors of Jovian Planets
No solid surface.
Layers under high pressure and temperatures.
Cores (~10 Earth masses) made of hydrogen compounds, metals & rock
The layers are different for the different planets. WHY?

11. The Jovian planets are principally made of hydrogen & helium, with composition very similar to the Sun.
Moving from the surface to the core:
temperature increases
pressure & density increases
At low temperatures and pressures characteristic of the outer layers of Jovian planets: Hydrogen is a diatomic gas (H2)
At higher pressures (few thousand km below the upper cloud deck): H2 becomes dissociated and undergoes a phase transition from the gaseous to a liquid state.

12. At pressures greater than 3 million atmospheres, H is squeezed so tightly that the atoms are separated into freely moving protons and electrons: liquid metallic hydrogen (LMH). This happens in Jupiter & Saturn
LMH is highly conducting (the electrons are highly mobile)
The combination of a metallic hydrogen interior and high rotation rates give Jupiter and Saturn strong magnetic fields.

13. 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.

14. Jupiter emits almost twice as much energy as it absorbs from the Sun.
accretion, differentiation, radioactivity can not account for it
Jupiter must still be contracting
Jupiter has 3 x more mass than Saturn, but is not much larger!
the added weight of H & He compresses the core to a higher density, just like stacking pillows

15. Jupiter emits almost twice as much energy as it absorbs from the Sun.
accretion, differentiation, radioactivity can not account for it
Jupiter must still be contracting
Jupiter has 3 x more mass than Saturn, but is not much larger!
the added weight of H & He compresses the core to a higher density, just like stacking pillows
Uranus & Neptune have less mass than Saturn, yet
they have higher densities
they must be made of denser material

16. Jovian planets are not quite spherical because of their rapid rotation

17. Jovian Planet Atmospheres

18. Jupiter’s Atmosphere
In 1995, the Galileo space probe plunged into the planet Jupiter!
It measured the atmospheric structure of Jupiter
thermosphere {absorbs Solar X-rays}
stratosphere {absorbs Solar UV}
troposphere {greenhouse gases trap heat from both Jupiter and the Sun}
These are the same structures found in Earth’s atmosphere.
Atmospheres are governed by interactions between sunlight and gases.

19. Jupiter’s Cloud Layers
Convection in the troposphere causes Jovian weather.
Warm gas rises to cooler altitudes, where it condenses to form clouds.
Three gases condense in the Jovian atmosphere:
ammonia (NH3)
ammonium hydrosulfide (NH4SH)
water (H2O)
They condense at different temperatures, so their differently colored clouds form at different altitudes.

20. 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

21. Convection in the troposphere, where the clouds form, coupled with rapid rotation of the Jovian planets leads to numerous bands of rising and falling air.
These are the colored “stripes” which we see in Jovian cloud structure.

22. Origin of Wind On the surface of Earth, winds are driven by
Pressure gradient force:
Air flows from high-pressure region to low pressure region.
Local air pressure are strongly influenced by differences in external heating.
Jupiter emits more energy than it receives from the Sun, indicative of internal heating.
Coriolis Effect:

23. Coriolis Effect
The Coriolis effect is an object’s apparent deflection of motion due to conservation of angular momentum
Moving south from point A to point B in the northern hemisphere causes an object to move farther from the rotation axis of the Earth. To conserve angular momentum, the object must rotate around the Earth’s axis slower than it did when it was further north.
The opposite occurs for objects when moving from B to A A L B L
Southern Hemisphere
Northern Hemisphere

24. Weather on Jupiter
The white bands are where rising air forms white ammonia clouds.
Strong east-west winds caused by strong coriolis (due to its high rotation rate of 10 hours) effect carry the clouds around the globe to form the stripes.
Snow from ammonia cloud depletes the atmosphere of ammonia cloud, allowing us to see deeper into the brown ammonium hydrosulfide clouds

25. The infrared image on the left clearly shows the temperature of the stripes – white bands are cold, and brown-reddish bands are hot (false color image).

26. 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

27. Saturn’s Atmosphere
Saturn is not as colorful or turbulent as Jupiter. This may be due to the fact that Saturn is cooler because it is further away from the Sun.
It does not contain storms as large as those seen on Jupiter, nor are they permanent.
It also has enough gravity to hold on to all the gasses and consists of 92.4% hydrogen, 7.4 % helium, and traces of methane and ammonia.

28. Atmospheres of Uranus and Neptune
Both planets have similar makeup to Jupiter and Saturn
Unlike Jupiter and Saturn, ammonia is not significant in either of these planets.
However, both planets have significant amounts of methane in their upper atmospheres - makes them appear blue.

29. Magnetic Fields
Strong fields, especially Jupiter. (20,000 X as strong as Earth’s field!)
Jupiter and Saturn have fields created by layer of metallic hydrogen.
Uranus and Neptune have weaker fields caused by core materials.

30. Magnetospheres
A planet’s magnetic field attracts and diverts the charged particles of the solar wind to its magnetic poles.
particles spiral along magnetic field lines and emit light (aurora); protective “bubble” is called the magnetosphere
The Earth is only terrestrial world with a strong magnetic field
solar wind particles impact the exospheres of Venus & Mars
solar wind particles impact the surfaces of Mercury & Moon

31. Jupiter’s Magnetosphere
Jupiter’s strong magnetic field gives it an enormous magnetosphere.
Gases escaping Io feed the donut-shaped Io torus.

33. Aurora

35. Jovian Planet Rings

36. The Rings of Saturn From Earth, they look solid.
concentric rings & Cassini division
From spacecraft flybys, we see thousands of individual rings.
separated by narrow gaps
differ in brightness & transparency
From within the rings, we would see many individual particles
size ranges from boulders to dust
reflective H2O ice (snowballs)
many collisions keep ring thin

37. Saturn’s rings are very thin, in some cases less than 100 meters thick.
The rings are not solid sheets but are made up of small particles of water ice or water- ice mixed with dust.
Three distinct rings are visible from Earth, and were named (outer to inner) A, B, and C. 33

38. The largest division between rings is known as the Cassini division.
This space is caused largely by the gravity of Mimas acting synchronously (2:1 resonance) on the orbital path of nearby ring particles.
Some other ring features are explained by the presence of small shepherd moons.
Mimas 33

39. View of the main rings in true color
Cassini
View of the main rings in true color C B A
Cassini
Division

40. The F ring: Confined by Shephard Satellites Prometheus
and Pandora
The A ring
Voyager
Cassini

41. Origin of Planetary Rings
Within 2 or 3 planetary radii of a planet, tidal forces will be greater than the gravity holding a moon together.
A moon which wanders too close will be torn apart.
Matter from the mini-nebula at this distance will not form moon.
Rings can not last the age of the Solar System.
Particles will be ground to dust by micrometeorite collisions.
Atmospheric drag will cause ring particles to fall into planet.
There must be a source to replenish ring particles.
gradual dismantling of small moons by collisions, tidal forces, etc.
The appearance of ring systems must change dramatically over millions or billions of years.

42. Roche Limit
The Roche limit is the minimum radius at which a satellite (held together by gravitational forces) may orbit without being broken apart by tidal forces.
Saturn’s rings are inside Saturn’s Roche limit, so no moons can form from the particles.
Source of ring material

43. Jupiter’s Rings Voyager I discovered a thin ring around Jupiter.
Voyager from
“behind” Jupiter
Jupiter’s Rings
Voyager I discovered a thin ring around Jupiter.
The ring is close to Jupiter, extending to only about 1.8 planetary radii.
The ring is thought to be replenished from the small moonlets within or near it.

44. Rings of Uranus & Neptune
The rings of Uranus and Neptune and are made of particles which are darker and smaller than that of Saturn.
The Uranian rings are narrow, a few of which are clearly confined by shepherding moons.
The Neptunian rings vary in width and are confined by resonances of some of the moons.

45. The other ring systems: fewer particles, smaller in extent, darker particles