this island earth - exploring the solar system reading: marshak, ch. 1 & 2
TRANSCRIPT
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 800oF; nighttime temps –280oF.
Mercury
Venus
• Resembles Earth in size, density, mass, etc.
•Tectonically Active
• Dense Atmosphere 90x Earth’s air pressure
• CO2-rich atmosphere
• “Runaway Greenhouse”: 475oC (900oF)
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 –125oC (-193oF).
• 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
LiquidRigid