1. Warm Up 3-2-15 Which inner planet is the hottest?
What’s so special about Mars?
What is the purpose of spending billions of dollars to explore outer space?
Agenda
-Turn in homework
-Notes Chp 27-3
-Outer Planets video
-Test Review Worksheet
Homework
Test Chp 26/27

2. Chapter 27-3 Outer Planets

3. The Jovian Planets

4. Space Craft Exploration of Jovian Planets
Voyager 1 and 2 left Earth in 1977 and reached Jupiter in March and July of 1979
Used Jupiter’s strong gravity to send them on to Saturn - gravity assist
Voyager 2 used Saturn’s gravity to propel it to Uranus and then on to Neptune
Studied planetary magnetic fields and analyzed multi-wavelength radiation
Both are now headed out into interstellar space
Galileo - launched in 1989 and reached Jupiter in December 1995
Two components: atmospheric probe and orbiter
Probe descended into Jupiter’s atmosphere and orbiter went through moon system
Cassini mission to Saturn arrived June 30, 2004
orbiter continues to orbit Saturn and its moons
Huygens probe launched from the orbiter January 14, 2005 to study Saturn’s moon Titan.
Background information Voyager is on going for 37 years

5. Jovian Planet Properties
Most of their mass is Hydrogen and Helium – light elements = low densities
High surface gravity allows their atmospheres to retain these light elements
Dense compact core at the center - no solid surface – gaseous atmosphere becomes denser (eventually liquid) at core
Differential Rotation – outer regions rotate at a different rate than the inner regions

6. Jovian Planet Properties
All Jovian planets have strong magnetic fields - rapid rotation and liquid conductive cores or mantles
Uranus has the most inclined rotational axis (extreme seasons)

7. Jupiter’s Atmosphere helium – 14%
molecular hydrogen – 86%
helium – 14%
small amounts of methane, ammonia, and water vapor
Darker belts lie atop downward moving convective cells Lighter zones are above upward moving cells. Belts are low-pressure, zones are high pressure
AsJupiter’s rotation causes wind patterns to move East/West along equator
Temperature difference between bands is main reason for color difference

8. Weather on Jupiter Main weather feature – Great Red Spot!
swirling hurricane winds
has lasted over 300 years
diameter twice that of Earth
rotates with planet’s interior
the spot appears to be confined and powered by the zonal flow
smaller storms look like white ovals
Discovered 7th or 8th century BC by the Babylonians (present day Iraq)

9. Saturn’s Atmosphere hydrogen 92.4% helium 7.4%
traces of methane and ammonia
Overall temperature is cooler than Jupiter
Thicker clouds result in less varied visible colors

10. Saturn’s Atmosphere
Cloud layer thickness is 3 times that of Jupiter (caused by lower surface gravity on Saturn)
9 main rings composed of dust and ice particles extend 6 million miles above the surface
62 known moons orbiting the planet
storm systems, and turbulent flow patterns
Cloud layer thickness is 3 times that of Jupiter (caused by lower surface gravity on Saturn) with winds reaching 600mi/hr
-Rings hypothesis made from nebula or destroyed moons with titans being the largest

11. Atmospheres of Uranus and Neptune
Hydrogen 84%
Helium 14%
Methane 2% (Uranus) 3% (Neptune)
Abundance of methane gives these planets their blue color.
Methane absorbs longer wavelength light (red) and reflects short wavelength light (blue)

12. Atmospheres of Uranus and Neptune
Few clouds in the cold upper atmosphere – featureless
Upper layer of haze blocks out the lower, warmer clouds
Neptune
Upper atmosphere is slightly warmer than Uranus (despite its further distance from Sun)
More visible features (thinner haze, less dense clouds lie higher)

13. Internal Structures – models that fit the data
Metallic hydrogen is like liquid metal
Uranus/Neptune
Saturn
Jupiter
Increasing temperature and pressure deeper in core
Jupiter bulges at radius (7% larger)
Saturn less asymmetric – larger core – same basic overall structure
Uranus/Neptune have a high density “slush” below cloud level - compressed water clouds

14. Pluto - and Charon Discovered in 1930 Charon (its moon) found in 1978
40 times the Earth’s distance from the Sun (40AU)
No spacecraft flybys but New Horizons mission launched in January 2006 will fly by in July 2015.
Only 20% the mass of our Moon
Similar in mass and size to Neptune’s large moon Triton
Probably formed in the Kuiper belt (comet birth place)
Highly inclined orbital plane
HST image of Pluto

15. Assignments
Notes Summary
Review Worksheet

16. Planet Travel Brochure
Each group of 2 needs
A travel brochure
Important information on your planet
Be creative!
You will be graded as a group, so choose wisely. (10pts)

17. Planet Travel Brochure (10pts)
Criteria: a) Cover page must have the planet name b) Draw a picture of the planet plus two other pictures c) Include the following facts: distance from the Sun, diameter, how many days in a year, surface temperature, atmosphere composition d) Cost of traveling there, living conditions, things to do (be creative) e) Create mock interviews with recent travelers (mock testimony) f) Must be colored and aesthetic looking

18.
Click on Run now

19. Kuiper Belt Objects compared
The discovery of Eris in 2005 showed that Pluto was not unique. These objects, along with Pluto, seem to be the largest of the Kuiper Belt objects.

20. The Earth The Moon solid inner core, liquid outer core
atmosphere ~ 50km thick
magnetosphere – charged particles in magnetic field
The Moon
no hydrosphere, atmosphere or magnetosphere
similar interior regions as Earth but no liquid core

21. Tidal Effects of the Moon on Earth
Even though the Sun exerts greater gravitational force on the Earth, tidal effects of the Moon are greater due to its closeness
Gravitational force exerted by the Moon is different on different parts of the Earth
The moon pulls the water
The moon also pulls the Earth
This causes two bulges - one on the side facing the moon and one on the opposite side where the water is “left behind”
Any point on the Earth experiences two high and low tides per day

22. Over time, tides have the following effects on the Earth and the Moon
Slowing the Earth’s rotation - the day is increasing by sec/century.
Increasing the size of the Moon’s orbit - its distance from the Earth is increasing by 4 cm/year (2 inch/year)
The moon is tidally locked to the Earth - the same side of the moon is always facing us (moon rotation period is the same as its orbital period)

23. Lunar Surface - lack of atmosphere and water preserves surface features
Maria – mantle material
“seas” - darker areas resulting from earlier lava flow
Basaltic, iron rich, high density (3300 kg/m3).
Highlands – crust material
elevated many km above maria
Aluminum rich, low density (2900 kg/m3).

24. Craters Caused by meteoroid impacts
Pressure to the lunar surface heats the rock and deforms the ground
Explosion pushes rock layers up and out
The ejecta blanket surrounds the crater
The rate of cratering on the moon is determined from the known ages of the highland and maria regions.
The Moon (and solar system?) experienced a sharp drop in the rate of meteoritic bombardment about 3.9 billion years ago (end of accretion era)
The rate of cratering has been roughly constant since that time

25. Formation of the Moon
The Moon has an overall composition and density quite difference from the Earth, but which resembles the material in the Earth’s mantle. This observation has led to the Impact Theory for the formation of the Moon.
Mars-sized body hit the molten Earth
Parts of the mantle blew off and later formed the moon
Earth had differentiated, so the mantle (from which the Moon formed) was already metal poor.

26. The laws of planetary motion were determined by Johannes Kepler in The planets’ orbits obey these three laws based on the effects of gravity. The Sun’s gravitational pull dominates the motions of all planets.
1st Law
3rd Law
2nd Law

27. The distances to planets are known from Kepler’s Laws
Sizes are determined from angular size and distance

28. Masses (and densities) - determined through observing the gravitational effect of the planet on some nearby object (moons, nearby planets, satellites)
Planets orbit the sun counter-clockwise as seen from the North Celestial Pole.
All planets are roughly in the same orbital plane EXCEPT Mercury (and the dwarf planet Pluto).

29. Terrestrial Planets Jovian Planets Mercury, Venus, Earth and Mars
Close to Sun
Small masses, radii
Rocky, solid surfaces
High densities
Slow rotation
Weak magnetic field
No rings
Few moons
Jupiter, Saturn, Uranus, and Neptune
Far from Sun
Large masses and radii
Gaseous surface
Low densities
Fast rotation
Strong magnetic field
Many rings
Many moons

30. Comets Dirty snowballs - dust and rock in methane, ammonia and ice
All light is reflected from the Sun - the comet makes no light of its own
The nucleus is a few km in diameter
Halley’s Comet in 1986
Long period comets take up to 1 million years to orbit the Sun (may originate in the Oort cloud)
Short period comets orbit the Sun in 200 years or less (e.g. Halley’s comet) – likely originate in the Kuiper belt and were kicked into an eccentric orbit

31. Comet Temple 1 image obtained from Stardust satellite flyby on Feb 14, 2011
Crater with a small mound in the center indicates cometary nucleus is fragile and weak.
Caused by impactor from Deep Impact mission in 2005 – found comet to be less icy and more dusty than expected...

32. Spring Meteor showers: Lyrids – Apr 21/22 Eta Aquarids – May 5/6
Meteoroids – interplanetary rocky objects smaller than 100m (down to grain size). Consist mainly of iron and nickel with some carbon
called a meteor as it burns in the Earth’s atmosphere
if it makes it to the ground, it is a meteorite
Old objects that appear to be as old as the solar system based on carbon dating
Most meteor showers are the result of the Earth passing through the orbit of a comet which has left debris along its path
Spring Meteor showers:
Lyrids – Apr 21/22
Eta Aquarids – May 5/6

33. Asteroids - rocks with sizes greater than 100m across
Most asteroids remain in the Asteroid belt between Mars and Jupiter but about 2000 have orbits that cross Earth’s path.
Based on known Earth-crossing asteroid orbits, it is estimated that 3 asteroids impact Earth every 1 million years!

34. Asteroid Watch (Near Earth Object Program)
Asteroid 2012 DA14 to Miss Earth on February 15, 2013
Asteroid 2012 DA14 (about 45 meters) will pass within about 3.5 Earth radii of the Earth's surface

35. Asteroids range in size from 100m to ~1000km
They are composed of carbon or iron and other rocky material.
The Asteroid belt is a group of rocks that appear to have never joined to make a planet (as opposed to having once been a planet that was later destroyed).
Too little mass
Different chemical compositions
Planet formation probably effected by nearby Jupiter’s strong gravity

36. Earth’s Atmosphere nitrogen (78%) oxygen (21%) argon (0.9%)
carbon dioxide (0.03%)
Protects the surface
Regulates temperature
Variables that describe a gas (P, ρ, T) are related by the Equation of State
P = (ρ/m)kT
m is average mass per particle = 29 x mass of proton. For T = 300K at surface, ρ = 1.1 x 10-3 g/cm3
Pressure at Earth’s surface (bottom of atmosphere) = 1 atm (or 1 bar)
1 atm = 106 dyn/cm2 (Like 100 people standing on a square meter!)

37. Earth’s Interior
Crust - 15 km thick (8 km under ocean km under continents)
Mantle km thick (80% of planet volume)
Core (3500 km outer core and 1300 km inner core) - High central density suggests the core is mostly nickel and iron
Density and temperature increase with depth
Density “jumps” between mantle and core but smoothly increases between inner and outer core – Why – changes in composition

38. Evolution of the Solid Earth
Accretion- material comes together to make the planet 4.6 Billion years ago (age of Sun). Earth was bombarded by interplanetary debris which made it hot.
Differentiation - different densities and compositions to the earth - Earth was molten, allowing higher-density material to sink to the core (this core material still has temperatures like that of the Sun!)
Crustal Formation - cooling and thickening of crust about 3.7 Billion years ago

39. The Surface of the Earth
The Earth is still active today: earthquakes, volcanoes…
Sites of activity outline surface plates - plate tectonics
Continental drift - few cm/year
Plates collide head on (mountains) or shear past (earthquakes)
Some plates are separating (under Atlantic) - new mantle material wells up between the
Convection of warm mantle material responsible for tectonics
Sites of earthquakes / volcanoes in the past 100 years

40. Earth’s Magnetosphere – space influenced by Earth’s magnetic field
Magnetic field lines run from the south to north magnetic poles
Magnetic poles are close to (but not the same as) the axis poles
The field is distorted by the solar wind
Field caused by the rotation of the planet coupled with the electrically conducting liquid metal core = dynamo effect
Aurora Borealis
Northern Lights – caused when the charged particles escape the magnetic field and collide with Earth’s atmosphere near the poles

41. Recycle Your Old Cell Phones
Reduce mining in DR Congo
Save the environment
2 points extra credit per cell phone (applicable to quiz or test)
Broken, unused, cracked screen – will accept in any condition