Transcript This Island Earth - Exploring the Solar System

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
Mercury
• No atmosphere
• No hydrosphere
• Tectonically “Dead”
• Heavily Cratered
•Slow rotation  179 days
• Noontime temps 800oF;
nighttime temps –280oF.
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)
Rigid Lithosphere
Plastic
Asthenosphere
Continental Crust –Intermediate
composition on average; thicker
(~20 – 80 km); less dense (~2.7);
higher; older (up to 4.0 b.y.)
Mantle –
Ultramafic
Rock
Rigid
Core –
Fe & Ni
Liquid
Solid