AST 1002 Week 5 Lecture + Textbook Notes
AST 1002 Week 5 Lecture + Textbook Notes AST 1002-Section 1
Popular in Planets, Stars and Galaxies (AST 1002-Section 1, Mark Riley)
Popular in Science
This 7 page Class Notes was uploaded by Katherine Ruiz on Sunday October 2, 2016. The Class Notes belongs to AST 1002-Section 1 at Florida State University taught by Mark Riley in Fall 2016. Since its upload, it has received 24 views. For similar materials see Planets, Stars and Galaxies (AST 1002-Section 1, Mark Riley) in Science at Florida State University.
Reviews for AST 1002 Week 5 Lecture + Textbook Notes
Report this Material
What is Karma?
Karma is the currency of StudySoup.
You can buy or earn more Karma at anytime and redeem it for class notes, study guides, flashcards, and more!
Date Created: 10/02/16
ASTRONOMY AST1002-0001 RILEY WEEK 5 WEEK 5 LECTURE NOTES THE TERRESTRIAL PLANETS + SATELLITES • Elon Musk • Venus rotates in the opposite direction from all other planets • Mercury o Angular distance greatest at 28° o Visible in sky 2 hours before sunrise and after sunset • Venus o Angular distance greatest at 47° o Visible 3 hours before sunrise SURFACES OF PLANETS • Mercury o Heavily cratered with smooth, low lying planes o No volcanoes o No atmosphere • Venus o Few 1000 craters o Many volcanoes- possibly active o Very thick atmosphere • Earth o Few 100 craters o Many active volcanoes o “Just right” atmosphere • Mars o Heavily cratered with smooth, low lying planes o Many volcanoes- all inactive o No atmosphere IMPACT CRATERS • Created when material falls from space and hits a planet’s surface • Shock wave forms from the point of impact • Creates a near perfect circle of a crater • It’s characteristic of large lunar craters to have central peaks due to the high speed of the impact CRATERING MEASURES GEOLOGICAL ACTIVITY • Not all planets and satellites show the same amount of cratering • Geological activity will erase cratering CRATERING AND RADIOMETRIC DECAY • You can get the age from a rock through radiometric decay • Almost all cratering happened in the first 1 billion years of the solar system • When impacts are so massive they can crack the crust which causes lava to flow out and fill the area of the crater leaving what is called MARIA SURFACE OF MERCURY • Very similar to Earth’s moon • Caloris Basin – 1550 km crater SEISMIC WAVES • Earthquakes create 2 kinds of waves o Pressure (P) Waves § Longitudinal § Slinky, spring § Sound waves are longitudinal o Shear (S) Waves § Transverse § Shaking a rope up and down o Sound travels much faster in solids than any other medium o P waves can travel through liquid and solid but S waves can only travel through liquid. They’re absorbed in other mediums o The speed of the wave depends on the density and the physical state of the material o Seismic waves follow curved paths because of the density and composition of Earth’s interior CHAPTER FIVE NOTES INTERSTELLAR CLOUDS • INTERSTELLAR CLOUD- the cloud of cool dust and gas in the space between stars • SELF GRAVITY- a gravitational attraction among all parts of the same object o Interstellar clouds have self-gravity • HYDROSTATIC EQUILIBRIUM-forces on a cloud are balanced • If the outward force of gravity is weaker or stronger, the cloud becomes unstable o Contracts when weaker than self-gravity o Expands when stronger than self-gravity • MOLECULAR CLOUDS- densest coolest interstellar clouds primarily composed of H molecules MOLECULAR-CLOUD FORMATION • Never uniform • Force of gravity inversely proportional to square of radius o Ex. ½ as far apart, 4x stronger ; ¼ as large, 16x stronger • As it collapses, gravitational forces become stronger • Collapses from inside out STARS AND PROTOSTARS • Innermost part of molecular-cloud eventually forms star, outermost part can form planets • PROTOSTAR-the innermost part of a collapsing molecular-cloud • Gravitational energy gets converted to thermal energy • Emits a lot of light but it’s difficult to see because the visible light is absorbed by the dust cloud • Most light is infrared • NEBULA-general term for interstellar cloud of gas and dust EVOLVING PROTOSTAR • Force of hot gas pushes outward, gravity pulls inward – exactly oppose each other • Loses thermal energy in radiation • Shrinking=heating up • “ignition” happens when the venter becomes hot enough to convert H-He o 10 million K • Mass determines whether it becomes a star • BROWN DWARF- “failed star” CONVERGENCE OF EVIDENCE • Early solar system FLAT • Planets orbit in same direction=material orbited in same direction • Large bodies created from accretion of smaller bodies • ACCRETION DISK-a disk that forms from the accretion of material around a massive object THE COLLLAPSING CLOUD + ANGULAR MOMENTUM • ANGULAR MOMENTUM- a conserved quantity of a revolving or rotating system with a value that depends on both the velocity and distribution of mass • Think of spinning skater • Amount of angular momentum depends on: o Speed of rotation. Faster=more a.m. o Mass of object. More mass=more a.m. o Distribution of mass in relation to axis. More spread out=more a.m. • CONSERVATION OF ANGULAR MOMENTUM-the angular momentum must remain the same in the absence of an external force FORMATION OF ACCRETION DISK • Can flatten without speeding up • Angular momentum is unchanged • Matter landing on disk becomes part of the star or is sent back into space CREATION OF LARGE OBJECTS • Small parts stick to large parts • Gentle bumping of objects to prevent shattering • PLANETESIMALS- “tiny planets” ROCK, METAL AND ICE • REFRACTORY MATERIALS- substances that are capable of withstanding high temperatures without melting or being vaporized o Only refractory substances exist in area closest to protostar • VOLITILE MATERIALS become gasses at moderate temperatures • Planet migration can occur ATMOSPHERES AROUND SOLID PLANETS • PRIMARY ATMOSPHERE- mostly H and He that is captured by a planet at the time of its formation • SECONDARY ATMOSPHERE-forms later in the life of a planet • COMETS- icy planetesimals that survive planetary accretion THE SOLAR SYSTEM CASE STUDY • Terrestrial planets- Mercury, Venus, Earth, Mars o Didn’t develop a thick atmosphere until secondary atmosphere formed • Giant planets- Jupiter, Saturn, Uranus, Neptune SEARCH FOR EXTRASOLAR PLANETS • EXTRASOLAR PLANET-a planet orbiting around a star other than the sun • First E.P.s discovered indirectly (gravitational pull on star) • Doppler Effect • Transit method-observing a planet passing in front of parent star • Gravitational lensing-star brightens as planet passes in front of it o VERY slight • Astrometry- measuring position of star in sky • Direct imaging-taking a picture of the planet directly CHAPTER SIX NOTES IMPACTS AND CRATERS • IMPACT CRATERING-a process resulting from the collision of solid planetary bodies- leaves distinct scars known as impact craters • Secondary craters can be created if the material falls back to the surface hard enough • METEOR VS METEORID VS METEORITE o Meteoroid-small cometary or asteroid fragments in space o Meteor-a meteoroid that burns up in a planetary atmosphere o Meteorite- meteoroids that survive to hit the ground • Micrometeoroids • Study craters to see history of planets surface CALIBRATING A COSMIC CLOCK • Geological activity erases craters • Moon has no atmosphere-can preserve up to 4 billion years of craters • Amount of cratering=age of surface • RADIOMETRIC DATING-finding the age of a rock by measuring the radioactive elements that decay into other elements • Almost all cratering took place in first 1 billion years INTERIOR COMPOSITION • Mass of Earth can be found by measuring Earth’s gravity • Density of surface is much smaller than density of planet=core is denser • Study meteorites formed at same time as Earth to determine core MODEL OF EARTH’S INTERIOR • Core composed of iron, nickel, dense materials • Not uniform in interior • DIFFERENTIATION-separating materials by density EVOLUTION OF PLANETARY INTERIORS • Evolution depends on temperature • Heat takes time to travel through rock, core is hotter than crust • Thermal energy lost through radiation • Rate of cooling is dependent on size • Hotter planet=more geological activity • Thermal energy not the only source of heating • Friction of tidal effects from moon and sun creates thermal energy • Core is solid because pressure is so great MAGNETIC FIELDS • MAGNETIC FIELD-created by moving charges and exerts a force on magnetically reactive objects • Geographic north pole is not magnetic north pole • Magnetic field of earth created by rotation on axis and a liquid outer core o Thermal energy-Magnetic energy • Mercury is the only other planet with a significant magnetic field PLATE TECTONICS • Alfred Wegener • Continents once joined together but drifted away • GPS confirms more precise movement • Motion of plates keeps Earth in a state of constant change ROLE OF CONVECTION • CONVECTION-transport of thermal energy by the movement of packets of gas or liquid • Earth’s mantle is mobile but not molten o Allows convection • Division of Earth’s crust o 7 major plates o 6 smaller plates • FAULT- fracture in a planets crust along which material can slide • HOT SPOTS-hot mantle material rises and releases thermal energy o Ex. Hawaiian Islands TECTONISM ON OTHER PLANETS • All terrestrial planets have evidence of tectonism TERRESTRIAL VOLCANISM AND TECTONISM • Fluid lava flowing from a single point can spread across a surface and form a shield volcano • Thick lava flowing with explosively generated rock deposits and creating a steep-sided structure are called composite volcanoes • Hot spots push mantle and lithospheric material up to the surface where it comes out as liquid lava VOLCANISM IN THE SOLAR SYSTEM • MARIA-dark areas that look like bodies of water o Vast hardened lava flows • Lava was too fluid on the moon=no volcanoes • Evidence Mars doesn’t have tectonic plates WEATHERING • First step in erosion • Rocks broken down, can be chemically altered • Radiation from the Sun and deep space creates erosion as well on Moon and Mercury since they have no atmosphere • Micrometeoroids chip rocks • Landslides on Mercury and Moon WIND EROSION • Earth, Mars, Venus have wind storms • Sand dunes on Earth and Mars and some on Venus • “Wind Vanes” tell direction of wind WATER EROSION • Earth= only planet with water • Dominates Earth’s erosion • Once water on mars o Where’d it go? § Escaped into atmosphere § Locked up in polar regions
Are you sure you want to buy this material for
You're already Subscribed!
Looks like you've already subscribed to StudySoup, you won't need to purchase another subscription to get this material. To access this material simply click 'View Full Document'