Our Earth is a very special place.
Seeds Of Life
Thank you liquid water!
Not too hot, not too cold!
Composition of the Earth’s primitive atmosphere
• First atmosphere (4.4-4.6 billion years ago): hydrogen and helium
Second atmosphere (4.4-4.0 billion years ago): water vapor, ammonia, and methane
Third atmosphere (3.3-4.0 billion years ago): 98% carbon dioxide, 2% water vapor and nitrogen
Volcanic eruptions and impacts from asteroids and comets may have created our primitive atmosphere
Thank you bacteria!
Cyanobacteria helped to produce oxygen and remove carbon dioxide
Current atmosphere (present day-3.3 billion years ago):
78% nitrogen and 21% oxygen
Thank you ozone layer!
Oxygen was important for producing ozone since ozone is O
The ozone formed before early life could move from the oceans onto dry land
The ozone protects the surface from hazardous UV radiation from the Sun
• Our Ozone is destroyed by CFCs which are chemicals produced by refrigeration, air conditioners, foam and aerosols
• They are very efficient at removing ozone
• Ozone slowly replenishes itself as it is created from sunlight and lightning
Thank you magnetic field!
The Earth’s magnetic field shields us from the stream of charged particles from the Sun and cosmic ray particles from space
Earth is the only terrestrial planet to have a significant magnetic field!
To have a significant magnetic field, the planet must:
1. Be a fast rotator- Earth takes 24 hours to rotate
2. Liquid metallic interior- Earth has outer molten iron core
Earth’s interior consists of a rocky mantle and an iron rich core
Earth’s surface is composed of about twelve major plates which slowly move relative to one another separation
Collision of two plates forms mountains
The San Andreas Fault
Plate tectonics is driven by convective currents in Earth’s mantle
Plate tectonics produced major changes to the
Earth’s surface over the past 200 million years
Earth in the Future
What would it be like to live on
Pangaea in the future?
• Will we get along?
• Country boundaries
• Animal Migration