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Warm Up 3-2-15 1. 1. Which inner planet is the hottest? 2. 2. What’s so special about Mars? 3. 3. 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
Chapter 27-3 Outer 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 rotation and liquid conductive cores or mantlesAll Jovian planets have strong magnetic fields - rapid rotation and liquid conductive cores or mantles Uranus has the most inclined rotational axis (extreme seasons)Uranus has the most inclined rotational axis (extreme 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 Neptune Uranus 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)
Internal Structures – models that fit the data Jupiter Saturn Uranus/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 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 Pluto
Planet Travel Brochure Each group of 2 needs Each group of 2 needs –A travel brochure –Important information on your planet Be creative! Be creative! You will be graded as a group, so choose wisely. (10pts) You will be graded as a group, so choose wisely. (10pts)
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
http://phet.colorado.edu/en/simulation/gra vity-and-orbits Click 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 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 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
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/m 3 ). Highlands – crust material elevated many km above maria Aluminum rich, low density (2900 kg/m 3 ).
Craters Caused by meteoroid impacts Caused by meteoroid impacts Pressure to the lunar surface heats the rock and deforms the ground Pressure to the lunar surface heats the rock and deforms the ground Explosion pushes rock layers up and out Explosion pushes rock layers up and out The ejecta blanket surrounds the crater 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 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 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 The rate of cratering has been roughly constant since that time
Formation of the Moon Mars-sized body hit the molten Earth Mars-sized body hit the molten Earth Parts of the mantle blew off and later formed the moon 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. Earth had differentiated, so the mantle (from which the Moon formed) was already metal poor. 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.
1 st Law 3 rd Law 2 nd Law The laws of planetary motion were determined by Johannes Kepler in 1609. The planets’ orbits obey these three laws based on the effects of gravity. The Sun’s gravitational pull dominates the motions of all planets.
Sizes are determined from angular size and distance distances The distances to planets are known from Kepler’s Laws
Masses 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).
Terrestrial 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 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 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
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 21/22 Eta 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 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) 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/cm 3 Pressure at Earth’s surface (bottom of atmosphere) = 1 atm (or 1 bar) 1 atm = 10 6 dyn/cm 2 (Like 100 people standing on a square meter!)
Crust - 15 km thick (8 km under ocean - 20-50 km under continents) Mantle - 3000 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 Earth’s Interior
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.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!)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 agoCrustal Formation - cooling and thickening of crust about 3.7 Billion years ago
The 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 - plate tectonicsSites of activity outline surface plates - plate 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 material wells up between theSome plates are separating (under Atlantic) - new mantle material wells up between the Convection of warm mantle material responsible for tectonicsConvection of warm mantle material responsible for tectonics Sites of earthquakes / volcanoes in the past 100 years
Earth’s Magnetosphere – 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 conducting liquid metal core = dynamo effectField 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
Recycle Your Old Cell Phones Reduce mining in DR Congo Reduce mining in DR Congo Save the environment Save the environment 2 points extra credit per cell phone (applicable to quiz or test) 2 points extra credit per cell phone (applicable to quiz or test) Broken, unused, cracked screen – will accept in any condition Broken, unused, cracked screen – will accept in any condition