This Island Earth - Exploring the Solar System Reading: Marshak, Ch. 1 & 2

Sol – Giver of Life * Bright enough but not too bright; massive enough, but not too massive. * Light emitted mostly in visible spectrum

Welcome to the ’Hood

Odd one Out – Pluto: a dirty snowball

The Gas Giants Saturn and its Moons

Jupiter 2.5 x as massive as all other planets combined, but low density (Sp. Gr. ~1.3) Composed mostly of hydrogen & helium. Fastest spin of any planet (10 hours). Ferocious wind storms (Great Red Spot) Io – one of just four volcanically active bodies in the solar system.

Asteroid Impact!

The Terrestrial Planets No atmosphere No hydrosphere Tectonically “Dead” Heavily Cratered Slow rotation  179 days Noontime temps 800 o F; nighttime temps –280 o F. Mercury

Venus Resembles Earth in size, density, mass, etc. Tectonically Active Dense Atmosphere  90x Earth’s air pressure CO 2 -rich atmosphere “Runaway Greenhouse”: 475 o C (900 o F)

Mars Tectonically “dead” today, but active in distant past. Much smaller than Earth with <1% Earth’s atmospheric pressure Can’t retain heat, avg. temps. Down to –125 o C (-193 o F). Contains some water – mostly in polar ice. Signs of water: rivers, oceans in past; where did water go?

This Island Earth – The Just-right Planet Close, but not too close to sun. Size – large enough to hold atmosphere, but not too much Tectonically active; magnetic. Atmosphere – dense, but not too dense; unusually oxygen-rich. Temperature – well-regulated in “livable range.” Water in three phases, oceans. Life!

A Look Inside the Earth Oceanic Crust –Thin (~5 km); dense (3.0); lower; younger (<180 my) Continental Crust –Intermediate composition on average; thicker (~20 – 80 km); less dense (~2.7); higher; older (up to 4.0 b.y.) Rigid Lithosphere Plastic Asthenosphere Core – Fe & Ni Mantle – Ultramafic Rock Solid Liquid Rigid