Transcript Formation of Solid Earth

Formation of the Solar System
The Nebular Hypothesis
• States that the sun and the planets condensed
at about the same time out of a rotation cloud
of dust and gas (SOLAR NEBULA)
• The solar nebula began to increase in
temperature and rotation and flatten into a
disk.
• The sun consists of 99% of all matter that was
contained in the solar nebula.
The Orion Nebula
1500 LY from Earth
Accretion
• One theory that describes how asteroids and planets
formed.
• As material moved around our young Sun (protosun),
the dust grains collided and began sticking together
to form larger rocks.
• Those rocks collided with other rocks and were held
together by gravity or broken off into pieces.
• Eventually these rocks combined into larger and
larger bodies, and eventually formed the plantets.
Formation of Planets
• PLANETESIMALS- Small bodies from which
planets originated in early formation
• PROTOPLANETS- Formed from collisions
between planetesimals and through the force
of gravity.
• Planetesimals and protoplanets formed by
ACCRETION
Formation of Solid Earth
Earth was HOT !!!!!
• 3 SOURCES OF ENERGY CONTRIBUTED
–Energy from planetesimal
collisions
–Energy produced by weight of
outer layer on inner layers
–Radioactive materials very
abundant when Earth formed and
emit high-energy particles
DIFFERENTIATION
• Denser materials
( like molten iron) sank
to the center of the
Earth and less dense
materials forced to
the outer layers.
• Earth formed three
distinct layers.
EARTH’S ATMOSPHERE
• Atmosphere formed because of differentiation
• Less dense gases, H and He• rose to the surface
• Earth’s gravity was too weak to hold onto
gases
• Earth’s magnetic field not fully developed
Outgassing
frequent volcanic eruptions releasing H2O vapor,
CO2, N, Methane (CH4), Sulfur dioxide (SO2), and
ammonia(NH3)
This formed our new atmosphere
And then……….
• Radiation from sun
cause ammonia and
water vapor to break
down
• H- escaped to space
• O- formed ozone O3
that shielded Earth
from UV radiation from
sun
Earth’s present atmosphere
• Organisms developed such as cyanobacteria
and early green plants (using CO2, releasing
O2)
• Amount of O2 increased (2 billion yrs ago this
increased rapidly)
• Composition of atmosphere 2 billion years ago
similar to present day
EARTH’S OCEANS
• Theory: icy bodies like comets collided with Earth
and the water from them became part of our
atmosphere
• Earth cooled vapor formed water and collected
• First ocean likely fresh water
• Over millions of years runoff from rainwater
dissolved chemicals from rocks and carried them
to oceans
• Water cycle through evaporation increased
salinity in the oceans over time.
Ocean’s effects on atmosphere
• Affect temperature by
dissolving CO2 and
affected early climate
helping to heat the
atmosphere
• The concentration of
CO2 in the atmosphere
has increased and
decreased over time
causing warmer and
cooler climates