Solar System Overview FYI … Distance Not To Scale …

The Sun At the Center (and we do go around it …..) 99.85% mass of Solar System 92% H / 8% He Source of solar wind and space weather

Inner Planets “Terrestrial Planets” Rocky Dense Metal cores (iron)

Asteroids “Minor planets” or “planetoids” or “planetesimals” less than 1000 km across Asteroid Belt between Mars and Jupiter Occasionally run into Earth and other planets (oops) Ida Encountered on Aug 28 th, 1993 by the Galileo Spacecraft, en route to Jupiter Dactyl

Asteroids Asteroids -> Meteoroid -> Meteor -> Meteorite km -> 10m-100 µm -> space rock trapped by gravity (burning up) -> space rock that actually hits the surface of a planet

Meteoroid fragment discovered in Argentina; on display at the Museum of Nature, Ottawa, Canada

Barringer Crater (Canyon Diablo) 1.2 kilometers wide 170 m deep ~ years ago Used by NASA during the 1960’s to prepare for moon landing Winslow, Arizona

Outer Planets Large! Gases and liquids No solid surface May have a small solid core Tumultuous atmospheres - rapid winds, large storms Rotate relatively quickly

Kuiper Belt Disk of debris at the edge of our Solar System Pluto is a KB Object (sorry!) Source of short- period comets

Oort Cloud A hypothesized sphere of comets surrounding the inner solar system and the kuiper belt ~ AU from the Sun Helps in explaining the regularity of comets within the Solar System

Inner Planets!

Smallest planet (0.4 Earth diam) Closest to Sun, moves around fastest (88 days) Surface -173 to 427 ºC ? Ice Caps – no tilt of axis so poles are cold No atmosphere Mariner 3 fly-bys in 1974 and 1975 – 40% of surface mapped Mercury #1, Coffee Bean

What are these? How did they form?

Venus #2, Large Blueberry Nearly the same size as Earth (.95) Slowest rotation of any planet (243 days) Spins backwards Surface temp 377 to 487 C Cloud covered – radar observations Dry! Very thick atmosphere mostly CO 2 Surface pressure is 100 times higher than Earth’s Runaway greenhouse Can see it in the night sky without a telescope!

Why is Venus hotter than Mercury?

Earth #3, Cherry 7900 mile (12756 km) diameter 23.5 degree axis tilt (seasons!) Surface temps –73 to 48 C Thick atmosphere, mild greenhouse effect Liquid water – lots! - at surface Can see it without a telescope!

Geologically active? Core, mantle, crust Magnetic field?

Who Cares About a Magnetic Field? We do!

Aurora Borealis

Aurora Austrailus

6794 km diameter (4,220 miles) – about ½ of Earth’s 25 degree axis tilt (seasons!) Rotates once every ~24 hours and orbits the Sun once every 687 days Very cold -83 to -33 C (-117 to -27 F) Thin atmosphere, 95% CO2, & 3% N Iron Oxide covers its surface (RED) Two small moons - Phobos (Fear) and Deimos (Terror) Hosting 5 functioning spacecrafts: Mars Odyssey, Mars Express, Mars Reconaissance Orbiter, Mars Rover: Opportunity and Curiosity Liquid water cannot exist on the surface of Mars due to low atmospheric pressure, except at the lowest elevations for short periods Mars #4, Pea Can see it in the night sky without a telescope!

North

South

The Gas Giants

89,000 miles (143,000 km) diameter – 11x Earth 2x mass of all other planets combined (318 x Earth); 100 pounds on Earth = 254 on Jupiter 90% H and 10% He (75/25% by mass) Methane, water, ammonia, rock Rocky core – liquid metallic hydrogen – electrical conductor, generates magnetic field Similar to Solar Nebula Jupiter #5, Small Cantaloupe

Cloud-tops average = -153°C = -244°F. 10 hour rotation / 12 year orbit Fly-bys: Pioneer 10, 11, Voyager 1, 2, Ulysses, Cassini Orbiter: Galileo – 8 years (recently “visited” the planet), Probe Jupiter Can see it in the night sky without a telescope!

Giant Red Spot – at least 300 years old 3 x size of Earth Winds up to 400 km / hr “Jr” Storms on Jupiter

Why Doesn’t Jupiter Blow Up?

9x the size of Earth 75% hydrogen and 25% helium Water, methane, ammonia and "rock“ Rocky core Winds up to 500 m / second -290 F Rings – 185,00 miles wide / /2 mi thick Water ice in rings 56 moons and counting 11 hour rotation / 29 year orbit Pioneer / Voyager Fly-by / Cassini/Huygens! Saturn #6, Large Orange

HST image; 1999

False Color Rather chilly in the rings Red: -261 F Blue -333 F Green -298 F Dirty Snow Turquoise= water ice Red = “dirty”

Titan! Clues to Early Earth?

Earth Titan

Titan Clues to Early Earth? Average surface temperature –179C Atmosphere of N (>90%), CH4, Ar Hydrocarbon-rich rivers/seas (ethane – C2H6) Water ice Atmosphere 1.5 x Earth

Uranus # 7, Kiwi First planet discovered with a telescope!

Uranus 4x the size of Earth 15% H, little helium – mostly ices Uniform through out; no rocky core Blue from methane absorption of red light (atmosphere) atmosphere has mostly hydrogen and helium 11 rings, 27 satellites -350 F at surface 18 hour rotation, 84 year orbit Spins on an axis inclined almost 90 degrees Voyager fly-by

Neptune #8, Apricot or nectarine

Neptune Ices and rock - 15% H and little He H, He, methane atmosphere (blue!) Uniform through out; small rocky core? Had storm “Great Dark Spot” MIA since Voyager 2 Pretty Good White Spot (Scooter) zipped around every 16 hours…. 4 Rings – unknown composition 13 moons 18 hour rotation / 165 year orbit Voyager (1989)

Pluto Grain of Rice

Pluto Diameter - 1,413 miles (2274 km) - 2/3 size of Earth’s Moon Rotation: 6 1/3 days Orbit: 248 years highly elliptical Sometimes is inside Neptune’s orbit (20 yrs) Light from Sun takes 5.5 hours to reach it Surface of water and methane ice, frozen nitrogen When closer to the Sun, heat produces an atmosphere

Is Pluto a Planet? Orbits a star Round Not a star or a moon “Cleared Out”/ “Dominates” its orbit What Makes a Planet a Planet?

Is Pluto a Planet? YesNo It has always been considered a planet Very small Very elliptical orbit Out of plane of ecliptic Same material as Kuiper belt objects Found other “non-planets” that were larger

August 24 th, 2006

New Horizons: Pluto-Kuiper Belt Mission January 2006 Launch! July 2015 – Pluto! – Kuiper Belt

Comets Dirty snowballs - small objects of ice, gas, dust, tiny traces of organic material

Comet Parts Nucleus, Coma Dust tail – white, “smoke,” reflects sun. 600,000 to 6 million miles long Ion tail – Solar UV breaks down CO gas, making them glow blue. 10’s of millions of miles

Hale-Bopp Comet First seen on July 23 rd, 1995 Read section 28.3 Q: 2, 3 Read section 28.4 Q: 2, 3, 4, 5