Chapter 2: Internal Energy and Plate Tectonics

What does our solar system begin as

Rotating spherical cloud of gas, ice, dust and debris

How does our solar system begin

• Particles accrete under gravity into a cloud

• Cloud contracts, speeds up, flattens into a disk

What accumulates by accretion most of disk’s matter and what is that matter

The sun (Hydrogen and helium)

What is nuclear fusion

Hydrogen turns to Helium and releases heat

Gravity sorts cloud into

Rings

What scrubs gas/liquid from terrestrials and what are the terrestrial planets

Solar heat (EM radiation) planets: Mercury, Venus, Earth, and Mars)

Giant planets collect and retain

Gas and liquid

International astronomical Union definition of a planet

1. Elliptical orbit

2. Large and dense enough to become spheroidal

3. No other planets or planetesimals in its orbit

What condition to be a planet does Pluto fail and why

Condition 3: no other planets or planetesimals in orbit because it crosses Neptune (eccentric orbit)

How was the moon formed

Mars-sized body collided with Earth

• Moon chemically similar to Earth’s crust and mantle

• Gases and liquids scrubbed

• Less dense than Earth (impact did not disturb iron rich core

Accretion mostly ceased how many billion years ago

4.6

What creates huge amounts of heat and what are the results of that

Processes of planet formation

• Impact energy

• Decay of radioactive elements

• Frictional energy from differentiation into layers under gravity