2. Earth's Place In Space
● Origin Of The Universe
– Big Bang Theory
– How our solar system formed
● Earth's Early Atmosphere
● Evolution
3. Origin Of The Universe
● Big Bang Theory
– Scientists believe that there was a giant
explosion around 12-14 billion years ago.
– Atomic particles from the explosion later
formed galaxies, stars, and planets.
4. Supernova
– 7 Billion years ago, a
supernova occurred
from one of the first
generations of giant
stars exploding.
– A supernova occurs at
the end of a stars life,
releasing huge
amounts of energy.
5. Solar Nebula
– The energy
released from the
first generation of
stars exploding,
produced a solar
nebula.
– A solar nebula is
thought to be a
spinning cloud of
dust and gas.
6. Solar Nebula
● Gravity caused the
spinning could of dust
and gas to collapse
and condense
forming our Sun in the
center.
● The other lumps of
matter that formed
from the contracting
dust and gas became
the planets.
7. Earth's Early Atmosphere
● 4.6 billion years ago, Earth was nothing more
than a molten ball of rock surrounded by an
atmosphere of hydrogen and helium.
● As the Earth cooled
enough to form a
solid crust, it was
covered with active
volcanoes.
8. Earth's Early Atmosphere
● These volcanoes spewed out gasses, like water
vapor, carbon dioxide, and ammonia forming
Earth's early atmosphere.
9. Earth's Early Atmosphere
● Very little oxygen
● No ozone layer
– Early life could only survive in the ocean (UV
radiation)
● Early organisms used energy from the Sun for
photosynthesis.
– Conversion of the suns energy into chemical
energy by living organisms.
– Oxygen was released as a byproduct.
10. Earth's Early Atmosphere
● As oxygen increased,
the ozone layer was
formed protecting
Earth from harmful
radiation.
● This allowed for plant
life to evolve and
made it possible for
the evolution of
animal life on land.
11. Evolution
● Precambrian:
Multicelled organisms
● Paleozoic: Reptiles
– Ice Age
● Mesozoic:
Dinosaurs/Mammals
● Cenozoic: Early
humans/Modern
Humans
