- The moon likely formed when a huge (~planet-size) world collided with Earth, and a chunk flew off.
- The moon’s materials match the composition and age of Earth’s except for those destroyed in great heat.
5 Stages of Terrestrial Planetary Evolution
(terrestrial = a planet you can stand on)
- Worlds become sphere
- Denser things go towards the center
- Earth has the Crust, Mantle (the majority), and Core (made of Iron)
- Outer core is liquid, inner core is solid
- We know what’s in Earth by measuring seismic waves during earthquakes
- Late Heavy Bombardment
- Geological Activity
- The Big Chill
- Fuel for volcanoes comes from nuclear fission (things breaking apart and releasing energy)
- This fuel is used up over time, and the amount of fuel is correlated with its size. After it runs out, volcanic activity stops, and that’s The Big Chill.
Electricity = Magnetism
- Earth’s magnetic field comes from moving molten rock inside of it.
- It creates a shield for Earth against damaging particles from solar winds.