Warm Up Warm Up 3-2-153-2-151. Which inner planet is the hottest?

2. What’s so special about Mars?

3. What is the purpose of spending billions of dollars to explore outer space?

AgendaAgenda-Turn in homework-Turn in homework-Notes Chp 27-3 -Notes Chp 27-3 -Outer Planets video-Outer Planets video-Test Review Worksheet-Test Review Worksheet

HomeworkHomeworkTest Chp 26/27Test Chp 26/27

Chapter 27-3Chapter 27-3Outer PlanetsOuter Planets

The Jovian Planets

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.

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

Jovian Planet Properties

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

Jupiter’s Atmosphere

• molecular hydrogen – 86%• helium – 14%

• small amounts of methane, ammonia, and water vapor

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

Saturn’s Atmosphere

• hydrogen 92.4%• helium 7.4%• traces of methane and ammonia

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

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)

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

Internal Structures – models that fit the data

JupiterJupiter SaturnSaturn Uranus/NeptuneUranus/Neptune

•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

Metallic hydrogen is like liquid metalMetallic hydrogen is like liquid metal

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 PlutoHST image of Pluto

AssignmentsAssignments

Notes SummaryNotes Summary Review WorksheetReview Worksheet

Planet Travel BrochurePlanet Travel Brochure Each group of 2 needsEach group of 2 needs

– A travel brochureA travel brochure

– Important information on your planetImportant information on your planet Be creative!Be creative! You will be graded as a group, so choose You will be graded as a group, so choose

wisely. (10pts)wisely. (10pts)

Planet Travel Brochure (10pts)Planet Travel Brochure (10pts)Criteria:a) Cover page must have the planet name b) Draw a picture of the planet plus two other picturesc) Include the following facts: distance from the Sun, diameter, how many days in a year, surface temperature, atmosphere compositiond) 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

http://phet.colorado.edu/en/simulation/http://phet.colorado.edu/en/simulation/gravity-and-orbitsgravity-and-orbits

Click on Run nowClick on Run now

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.

The Earth

• 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

Tidal Effects of the Moon on EarthTidal Effects of the Moon on Earth

The moon pulls the water The moon pulls the water

The moon also pulls the The moon also pulls the EarthEarth

This causes two bulges - one This causes two bulges - one on the side facing the moon on the side facing the moon and one on the opposite side and one on the opposite side where the water is “left where the water is “left behind”behind”

Any point on the Earth Any point on the Earth experiences two high and experiences two high and low tides per daylow tides per day

Even though the Sun exerts greater gravitational force on the Earth, tidal effects Even though the Sun exerts greater gravitational force on the Earth, tidal effects of the Moon are greater due to its closenessof the Moon are greater due to its closenessGravitational force exerted by the Moon is different on different parts of the EarthGravitational force exerted by the Moon is different on different parts of the Earth

Over time, tides have the following effects on the Earth and the Moon

• Slowing the Earth’s rotation - the day is increasing by 0.002 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)

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).

Craters

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

Formation of the Moon

• Mars-sized body hit the Mars-sized body hit the molten Earthmolten Earth

• Parts of the mantle blew off Parts of the mantle blew off and later formed the moonand later formed the moon

• Earth had differentiated, so Earth had differentiated, so the mantle (from which the the mantle (from which the Moon formed) was already Moon formed) was already metal poor.metal poor.

The Moon has an overall composition and density quite difference from the 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 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. has led to the Impact Theory for the formation of the Moon.

11stst Law Law 33rdrd Law Law22ndnd Law Law

The laws of planetary motion The laws of planetary motion were determined by were determined by Johannes Johannes Kepler Kepler in 1609. The planets’ in 1609. The planets’ orbits obey these three laws orbits obey these three laws based on the effects of gravity. based on the effects of gravity. The Sun’s gravitational pull The Sun’s gravitational pull dominates the motions of all dominates the motions of all planets.planets.

SizesSizes are determined from are determined from angular size and distanceangular size and distance

The distancesdistances to planets are known from Kepler’s Laws

MassesMasses (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).

Terrestrial PlanetsTerrestrial 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

Jovian PlanetsJovian Planets

•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

Comets Dirty snowballs - dust and rock in methane, ammonia and iceAll light is reflected from the Sun - the comet makes no light of its ownThe 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

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...

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 21/22Eta Aquarids – May 5/6

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!

Asteroid Watch (Near Earth Object Program)http://neo.jpl.nasa.gov/

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

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

Earth’s AtmosphereEarth’s Atmosphere •nitrogen (78%)nitrogen (78%)•oxygen (21%)oxygen (21%)•argon (0.9%)argon (0.9%)•carbon dioxide (0.03%carbon dioxide (0.03%))

•Protects the surfaceProtects the surface•Regulates temperatureRegulates temperature

Variables that describe a gas (P, ρ, T) Variables that describe a gas (P, ρ, T) are related by the Equation of Stateare related by the Equation of State

P = (ρ/m)kTP = (ρ/m)kT

m is average mass per particle = 29 x m is average mass per particle = 29 x mass of proton. For T = 300K at mass of proton. For T = 300K at surface, ρ = 1.1 x 10surface, ρ = 1.1 x 10-3-3 g/cm g/cm33

Pressure at Earth’s surface (bottom of Pressure at Earth’s surface (bottom of atmosphere) = 1 atm (or 1 bar) atmosphere) = 1 atm (or 1 bar) 1 atm = 101 atm = 1066 dyn/cm dyn/cm22 (Like 100 people (Like 100 people standing on a square meter!)standing on a square meter!)

Crust Crust - 15 km thick (8 km under ocean - 20-50 - 15 km thick (8 km under ocean - 20-50 km under continents)km under continents)

Mantle Mantle - 3000 km thick (80% of planet volume)- 3000 km thick (80% of planet volume)

Core Core (3500 km outer core and 1300 km inner (3500 km outer core and 1300 km inner core) - High central density suggests the core is core) - High central density suggests the core is mostly mostly nickelnickel and and iron iron

Density and temperature increase with depthDensity and temperature increase with depth

Density “jumps” between mantle and core but Density “jumps” between mantle and core but smoothly increases between inner and outer core smoothly increases between inner and outer core – Why – changes in composition– Why – changes in composition

Earth’s InteriorEarth’s Interior

Evolution of the Solid EarthEvolution of the Solid Earth

•AccretionAccretion- material comes together to - material comes together to make the planet 4.6 Billion years ago make the planet 4.6 Billion years ago (age of Sun). Earth was bombarded by (age of Sun). Earth was bombarded by interplanetary debris which made it hot.interplanetary debris which made it hot.

•DifferentiationDifferentiation - different densities and - different densities and compositions to the earth - Earth was compositions to the earth - Earth was molten, allowing higher-density material molten, allowing higher-density material to sink to the core (this core material to sink to the core (this core material still has temperatures like that of the still has temperatures like that of the Sun!)Sun!)

•Crustal FormationCrustal Formation - cooling and - cooling and thickening of crust about 3.7 Billion thickening of crust about 3.7 Billion years agoyears ago

The Surface of the EarthThe Surface of the Earth

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

Sites of Sites of earthquakes earthquakes / volcanoes / volcanoes in the past in the past 100 years100 years

Earth’s Magnetosphere Earth’s Magnetosphere – space influenced by Earth’s magnetic field– space influenced by Earth’s magnetic field

•Magnetic field lines run from the south to north magnetic polesMagnetic field lines run from the south to north magnetic poles•Magnetic poles are close to (but not the same as) the axis polesMagnetic poles are close to (but not the same as) the axis poles•The field is distorted by the solar windThe field is distorted by the solar wind•Field caused by the rotation of the planet coupled with the electrically Field caused by the rotation of the planet coupled with the electrically conducting liquid metal core = dynamo effectconducting liquid metal core = dynamo effect

Aurora BorealisAurora BorealisNorthern Lights Northern Lights – caused – caused

when the charged particles when the charged particles escape the magnetic field and escape the magnetic field and

collide with Earth’s collide with Earth’s atmosphere near the polesatmosphere near the poles

Recycle Your Old Cell PhonesRecycle Your Old Cell Phones Reduce mining in DR CongoReduce mining in DR Congo Save the environmentSave the environment 2 points extra credit per cell phone 2 points extra credit per cell phone

(applicable to quiz or test)(applicable to quiz or test) Broken, unused, cracked screen – will Broken, unused, cracked screen – will

accept in any conditionaccept in any condition