I.Overall Properties of Solar System: 1.Nearly co-planar orbits (disk-shaped) 2.All planets orbit Sun in same direction as Sun’s rotation 3.MOST (but not all) planets rotate in same direction as their obits around Sun 4.Planets: Small dense terrestrial planets in inner SS Large, low density, Jovian planets in outer SS Pluto is exception(Cont.) Outline Ch.6: Solar System

I.Overall Properties (cont): 5.In general: closer to Sun, larger density 6.Hot near Sun, cold far away 7.Composition of Solar Nebula II. Extrasolar Planets Are there planets around other stars? YES (more than 450 so far) Outline Ch.6 (Cont.)

7. Composition of Solar Nebula: 98% Hydrogen & Helium, 2% other elements Condensation of solids from nebula: Inner part is hot, only high density materials (metals and silicates) can condense Outer regions cooler, can condense lower density materials like water ice and other ices Near Sun: terrestrial planets Far from: Sun Jovian planets I. Overall Properties (cont):

Condensation of Solids from Solar Nebula

II.Extrasolar Planets More than 500 detected Most detected indirectly using radial velocity and transits in front of stars Types of planets: most are strange (because those are the ones we can detect). How are they strange? Look it up Outline Ch.8 (Cont.)

I.Earth as a planet (from Space) II.Atmosphere: composition, greenhouse effect. III.Surface Activity. Plate Tectonics (continental drift and seafloor spreading), volcanism, impacts, erosion IV.Interior. Earthquakes, hot interior (radioactivity) molten metallic core, magnetic field. Outline of Earth (Ch. 7 part I )

Comparing the Terrestrial Planets

CO 2, Water, Oxygen, Life VenusMarsEarth Carbon Dioxide 98%95%0.03% Nitrogen1.9%2.7%78% Oxygen<<0.1 % 0.13%21% Surface Temp 477ºC-53ºC13ºC Atmospheri c Pressure (bars) Water: dry dry surface wet

A couple of questions… Where did the CO 2 go? The Earth probably had bars (60-90 times the current atmosphere) of CO 2 in the atmosphere….where is it? Dissolved by oceans and into sedimentary rocks (we’re standing on it) When did the atmosphere become oxygen- rich? Photosynthesis

Greenhouse Effect H 2 O, CO 2, CH 4 etc. Let UV and visible light through Trap infrared light Small changes in concentrations can cause large climatic changes

Earthquakes and Volcanoes are mainly along plate boundaries: Earth’s crust in motion

How do we know about Earth’s interior? We study Earthquakes: P-waves S waves (do not penetrate liquids) Molten metal core and semi-liquid mantle Currents in Earth’s molten core generate the magnetic field

Interior heat drives the motion on the surface of the Earth

Impact Processes Have occurred on Earth as much or more than on the Moon Famous craters on Earth: Meteor Crater in Arizona (~20,000 years ago) Chicxulub in Yucatan (~65 million years ago) at K/T boundary: caused disappearance of 2/3 of species including dinosaurs. Most craters on Earth have been eroded by rain, glaciers and wind

Overall properties Atmosphere. 77% N, 21% O, all others 2%. Greenhouse effect. Interior. Earthquakes, hot interior (radioactivity) molten metallic core, magnetic field. Surface Activity. Plate Tectonics (continental drift and seafloor spreading), earthquakes, volcanism, impacts (now and in past), erosion. Summary of Earth

Chapter 7 Part II The Other Terrestrial Planets

Comparing the Terrestrial Planets Venus is still geologically active The larger the planet, the longer it stays geologically active

Overall Properties of these Planets I.Mercury: innermost planet, no atmosphere, surface characteristics, slow rotation, very weak magnetic field II.Venus: Earth’s twin, atmosphere, surface, interior, rotation, magnetic field, evolution III.Mars: atmosphere, surface, interior, rotation, magnetic field, evolution, two moons (Phobos Deimos), life on Mars? IV.Moon Outline Ch. 7 Mercury, Venus, Mars, Moon

I.Mercury: innermost planet, terrestrial No atmosphere Surface: cratered, with scarps (cliffs) indicating shrinkage of the planet (metal core cooled and shrank) Interior: large metal core (most of Mercury’s radius is the metal core) Rotation: very slow Very weak magnetic field (why, in spite of large metal core?)

Did Mercury shrink? Steep long cliffs formed when the core cooled, shrinking the planet by ~20 km. Mercury is probably geologically dead.

II. Venus: Earth’s twin, atmosphere 90x thicker than Earth’s and mostly CO 2, sulfuric acid clouds and rain Surface: volcanic and relatively young Interior: probably similar to Earth Rotation: very slow and retrograde Magnetic field: weak (why?) Evolution: no water, lots of CO 2 in atmosph.  greenhouse  very hot

Atmospheres of Earth and Venus

Radar images of Earth and Venus No indication of plate tectonics on Venus

PlanetDistanc e (AU) Mass (Earth = 1) MoonsDensity (Water =1) Mercury Venus Earth Mars Jupiter Saturn Uranus Neptune Pluto

Mars: Atmosphere 100x thinner than Earth’s and mostly CO 2. Some water ice in poles and below the surface, evidence of liquid water and thicker atmosph. in past Surface: volcanic and cratered, largest volcano in SS (Olympus Mons), very large canyon (Valles Marineris) evidence of liquid water in past (dry riverbeds and lakes) Interior: probably solid and geologically inactive (smaller planets cool faster). i.e., Olympus Mons is an exticnt volcano Rotation: almost same as Earth (once every 23 hrs) Rotation axis, about the same tilt as Earth. Does Mars have seasons? Magnetic field: weak (why?) Evolution: smaller size, lost most of its atmosph.  lost surface water. Smaller size, interior cooled faster, no more geologic activity Moons, Phobos and Deimos

Mars from Spacecraft

Mars’ Moons: Phobos and Deimos Captured asteroids

Chapter 8 Part I Jupiter and Saturn

I.Overall Properties of these Planets II.Jupiter : Composition, atmosphere, interior, rotation, magnetic field, moons, ring, impact of comet SL9 in III.Saturn: Composition, atmosphere, interior, rotation, magnetic field, moons, rings. Outline Ch. 8 part I

I.Overall Properties of these Planets Largest in SS Thick atmospheres, mostly H and He, with CH 4 (methane), NH 3 (ammonia) and other molecules Liquid hydrogen interiors Lower density than terrestrial planets Strong magnetic fields, rings and many moons Jupiter and Saturn (Ch. 8 part I)

Composition : H, He, CH 4, NH 3, etc. Atmosphere: very active, belts, zones, red spot Interior: liquid hydrogen and metallic hydrogen Rotation: fast (9.8 hrs) Magnetic field: strongest in SS Moons: Four Galilean satellites (miniature SS) plus many other moons Ring: dark and faint impact of comet SL9 in Jupiter

Jupiter’s Atmosphere See animation in book (Ch. 8 )

Less mass less gravity less compression. The physical states of the cores of the less massive jovians are less extreme (probably no metallic hydrogen inside of U and N). Interiors

Io’s Volcanoes Io is heated by the tides with Jupiter

Europa May have an ocean of liquid water under its icy surface. Life there?

Composition : H, He, CH 4, NH 3, etc. Atmosphere: less active than Jupiter, belts, zones Interior: liquid hydrogen and metallic hydrogen Lowest density (would float on water) Rotation: fast (11 hrs) Magnetic field: strong (but not as much as Jupiter) Ring: largest and brightest in SS. Composed of many icy particles Moons: largest is Titan has a thick atmosphere, plus many other moons NASA’s Cassini Spacecraft currently studying Saturn Saturn

Saturn’s Moons: Titan has an atmosphere of nitrogen and methane

I.Uranus and Neptune: Discoveries, atmospheres, interiors, rotation, magnetic fields, moons, rings, Uranus’ axis tilt and seasons. II.Pluto and Charon: Orbit, composition, moon, why so different from Jovian planets? III.Transneptunian Bodies (the Kuiper belt) Outline of Uranus, Neptune and Pluto (Ch.8 part II)

Composition : H, He, CH 4, NH 3, etc. Atmospheres: less active, dark spot on Neptune Interior: liquid hydrogen but no metallic hydrogen Rotation: fast (~17 hours for both) Magnetic field: strong (but not know how it is produced) Moons: many moons, Neptune’s Triton is larger than Pluto and retrograde (probably captured) Rings: dark and faint I. Uranus and Neptune

PlanetDistanc e (AU) Mass (Earth = 1) MoonsDensity (Water =1) Mercury Venus Earth Mars Jupiter Saturn Uranus Neptune Pluto

Triton: largest of Neptune’s moons Larger than Pluto and in a retrograde orbit

II.Pluto and Charon: Orbit, composition, moon, why so different from Jovian planets? Outline of Uranus, Neptune and Pluto

Pluto and its three Moons

III.Transneptunian Bodies (the Kuiper belt): Many objects smaller than planets: similar to the asteroid belt Largest object is slightly larger than Pluto Source of some of the comets Triton may have formed in the Kuiper belt was captured by Neptune Outline of Uranus, Neptune and Pluto (Ch. 8 part II)

COMETS AND THEIR COMPOSITION (Ch. 9 part I)

OUTLINE I. Nature of Comets II. Comets and the Origin of Earth’s Water III.Dust Composition

. Comet Ikeya-Zhang March 2002.

Nature of Comets (Cont.) Two Known Sources of Comets Oort Cloud (spherical shell ~ 50, ,000 AU) Kuiper Belt (disk ~ AU) (Astronomical Unit [AU] = Earth-Sun Distance)

Oort Cloud ~10 5 AU Sun About 1/3 distance to nearest star

Kuiper Belt ~50 AU Sun Neptune’s Orbit

Impact of Comet SL9 with Jupiter in 1994

Why is Earth rich in water and where did this water come from? Comet impacts? Asteroid impacts? Probably both: The composition Earth’s water is consistent with a cometary origin of at least some of it. In addition, some asteroids can have as much as 15% water IV. Comets and Origin of Earth’s Water

VI.SUMMARY OF COMETS Comets are composed mainly of H 2 O ice plus cosmic dust and other ices The main features of a comet are the nucleus, coma and tails There are two known sources of comets: Oort Cloud and Kuiper Belt The chemical composition of comets (rich in deuterium) is consistent with a cometary origin of at least some of Earth’s water and organic molecules

Asteroids and Meteorites Ch9 part II

Asteroids and Meteorites Outline I.Introduction II.Asteroids Orbits, sizes, composition III. Meteorites Irons Stony-Irons Stones IV.Origin of Meteorites V. Meteorites and the Solar System VI.Summary

Asteroids, comets and meteorites are the smallest members of the solar system All these objects tell us much about how the rest of the solar sytem formed I.INTRODUCCION

Most have orbits between between Mars and Jupiter Some have orbits that cross Earth’s, these are known as Earth-crossing asteroids They have collided with Earth and they are likely to do so again. The largest asteroid is Ceres II.ASTEROIDS

Irons Stony-Irons Stones (~75% of all meteorites) III. Types of Meteorites

Irons are excavated by collisions Stony-Irons are excavated by collisions III. Types of Meteorites Iron Iron and stone Stone Diferentiated Asteroid Non-diferentiated Asteroid

III.Origin of Meteorites Asteroids (more than 95%) Asteroids collide with each other and breakup, some of those fragments become meteorites Mars (a few percent) Impacts on Mars kick martian material into space and some ends up falling on Earth Moon (a few percent) Also because of impacts

IV. Meteorites and the Solar System Age of Solar System (4.6x10 9 years) determined from radioactive dating of meteorites Meteorites and Planets: Information about asteroids, Mars, Moon. Information about interior of Earth, e.g., iron core.

V. Summary of Asteroids and Meteorites Most asteroids orbit the Sun between Mars and Jupiter Some asteroids cross Earth’s orbit and eventually collide with Earth Ceres is the largest asteroid There are several types of asteroids Meteorites are solid objects from space that reach the Earth’s surface Most meteorites are from asteroids, a few are from Mars and the Moon. Most meteors are from comets Three types of meteorites: Irons, Stony-irons, Stones Meteorites tell us about the rest of the solar system.