The Earth's Unique Journey to Life

Introduction

• Earth is the only known home to life in the universe.
• Understanding Earth's uniqueness requires traveling back in time.
• The journey starts 5 billion years ago with a newborn Sun.

Formation of Earth

• Gravity formed Earth from dust and rocks around the Sun.
• Earth initially resembled a boiling ball of liquid rock.

Creation of the Moon

• A collision with a Mars-sized planet formed the Moon.
• The Moon formed from debris, initially much closer to Earth.

Early Earth Conditions

• Earth cooled from a molten state, forming a crust.
• Meteors brought water and essential minerals, sparking life's ingredients.

Emergence of Life

• 3.5 billion years ago, stromatolites (bacteria) began photosynthesis, releasing oxygen.
• Oxygen transformed iron and the atmosphere, paving the way for complex life.

Plate Tectonics and Supercontinents

• Earth's crust broke into plates, forming continents like Rodinia.
• Movement of these plates reshaped the planet over millions of years.

Snowball Earth

• 650 million years ago, Earth experienced its longest ice age.
• CO2 build-up from volcanoes eventually melted the ice, increasing oxygen.

Cambrian Explosion

• 540 million years ago, diverse ocean life forms emerged.
• Oxygen allowed for larger creatures with skeletons.

Life on Land

• Ozone layer formed, protecting life from UV radiation.
• First land plants appeared, increasing oxygen levels.
• Amphibians and then reptiles colonized land.

Massive Extinctions and Survival

• The Permian extinction wiped out 95% of life.
• Dinosaurs rose to dominance afterward.

Breakup of Pangea and Formation of Oceans

• Pangea split, giving rise to continents and oceans we know today.
• Geological activities led to the creation of oil from ancient fish.

Rise of Mammals After Dinosaur Extinction

• An asteroid impact led to the extinction of dinosaurs 65 million years ago.
• Mammals, including primates, became dominant species.

Evolution of Early Humans

• Changes in Africa's climate influenced ape evolution to bipedalism.
• Homo erectus marked early human ancestors leaving footprints.

Ice Ages and Human Migration

• Ice ages shaped the Earth's landscapes and facilitated human migration.
• Land bridges allowed movement from Asia to the Americas.

Conclusion

• Earth's journey is marked by catastrophes and triumphs, shaping life.
• The story is ongoing, with more changes and evolution expected over billions of years.