Formation of the Solar System
Chapter 27 section 1
Objectives
• Explain the ___________________ of the origin of the
solar system.
• Describe the formation of the __________
_________________________________ of Earth.
Definitions
• ______________________- the sun and all of the planets
and other bodies that travel around it
• __________________- any of the primary bodies that orbit
the sun
The Nebular Hypothesis
• ____________- a rotating cloud of gas and dust
• ____________________________- rotating cloud of gas and dust
from which our sun and the planets of our solar system formed
• The sun contains about _____________ of the material that was
contained in the solar nebula
How Did It Start?
• During rotation, _____________________
__________________________________
__________________________________caused the
center of the nebula to become very hot.
• At ~ ______________________ hydrogen fusion began.
Formation of the Planets
• As the sun formed in the center the planets formed to the outside in
3 stages.
• ____________________________- small bodies from which
planets originated—joined together through collisions & gravity to
form
• _____________________- large bodies made of planetesimals—
large body = ______________________________
• Protoplanets condensed to form planets and some moons.
The Inner Planets
• _______________________________________________
_____________________
• Contain lots of heavy elements—
________________________________
• Lost less dense gases—not enough
_______________________ to hold them
• All have solid surfaces and are _________ and
____________ than the outer planets
The Outer Planets
• _______________________________________________
_____________________
• Formed far from the sun and did not lose
___________________________
• Called _____________________ because they are
composed mostly of gas. They have low density and are
HUGE.
Pluto
• Farthest from the sun
• Tiny—smaller than __________________
• Ice ball made of frozen
__________________________________
• No longer a planet more on this in section 4
Formation of Solid Earth
• When Earth first formed, it was extremely
___________________ because of:
– ______________________ produced when planetesimals
collided
– Increased ____________________ of outer layers compressing
inner layers
– Abundance of _________________________
______________________________
Early Solid Earth
• Formed through _________________________
• Differentiation- process through which dense material sinks to the
______________________ and forces less dense material to the
______________________________________
– __________________- dense center of iron & nickel
– ________________- thick layer of iron & magnesium rich rock
– _______________- thin outermost layer of less dense silica rich rock
Present Solid Earth
• Surface cooled enough for ____________
________________ to form
• Surface continued to change because of
– ____________________________________
– ____________________________________
– Interactions with the forming _____________
______________________
Formation of Earth
•
•
•
•
•
•
Solar nebula—spinning & becoming warm near the center
↓
Planetesimals form
↓
Gravity causes planetesimals to collect more nebular material
↓
Protoplanets form then condense to form planets and some moons
↓
Very hot Earth with 3 energy sources: (1) planetesimal collisions, (2) compression of inner layers, (3)
radioactive materials
↓
Earth began to cool and experience differentiation: core- iron & nickel, mantle- iron & magnesium, crustsilica rich rock
•
↓
Earth’s surface cooled enough for solid rock to form—changes continue due to interior heat, impacts, &
atmospheric interactions
Formation of Earth’s Atmosphere
• Earth’s atmosphere formed because of
_________________________________.
• Least dense materials (_______________
____________________) rose to the surface and formed
our original atmosphere.
Early Atmosphere
• Original atmosphere was made of hydrogen & helium.
• As the sun heated the gases, they began to expand and
move rapidly.
• Earth’s gravity wasn’t ________________
__________________________________
• Hydrogen and helium were probably blown away by the
solar wind.
Outgassing
• ___________________- process whereby gases were
expelled by Earth.
• Main gases released were H2O vapor, CO2, N2, CH4, SO2,
& NH3
Present Atmosphere
• Organisms that were able to survive the early atmosphere
developed—mainly bacteria and plants—used CO2 for
______ _________________________ which left us with
an oxygenated atmosphere.
• About __________________ years ago, the atmosphere
reached its present composition
Formation of Earth’s Oceans
• Most of the water started out as comets—icy bodies--got too close
to the ________ ________________________ early Earth.
• Because of the heat, the water _____________ and became part
of the ___________________.
• As Earth cooled, the water _________________ and fell as
_______________.
• As it ran over the surface, _________________ dissolved in the
water.
The Oceans’ Effects on the Atmosphere
• Oceans keep _______________________ down by
dissolving and holding __________________.