12.3 Origin of Life KEY CONCEPT The origin of life on Earth remains a puzzle.
Earth Origin Slideshow
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Transcript of Earth Origin Slideshow
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GEOL 150 Earth Revealed - Winter 2014
Instructor: Kim Bishop
Office: La Kretz Hall Rm 116
Phone: (323) 343-2409
email: [email protected]
Origin of the Earth and Solar System
What is the Solar System?Solar System
• Sun
• Planets
• Moons
• Asteroids
• Meteors
• Comets
Our Solar System is defined as our Sun and the variousobjects that orbit around the Sun.
Our Sun at the center of the Solar System is one star
of billions that make up the Milky Way galaxy. A
galaxy is a huge, disk-shaped, rotating mass of
billions of stars.
The Milky Way galaxy is one of billions of galaxies that
exist within the Universe.
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There are important characteristics of the Solar
System that need to be accounted for in a reasonable
hypothesis for the origin of the Solar System
What are these characteristics?
1) The planets and other objects orbit the sun in
approximately the same plane.
2) The planets and other objects orbit the sun in
the same direction.3) The planets revolve around their axes in the
same direction as they orbit the sun
4) The 4 inner planets (Mercury, Venus, Earth,
and Mars) are small and “rocky” compared to the
4 outer planets (Jupiter, Saturn, Venus, &
Neptune), which are large and gaseous.
Note that Pluto is now
considered a “dwarf
planet”, not a planet.
Important Characteristics of the Solar System that need to be
accounted for in a reasonable hypothesis for the origin of the
Solar System
1) The planets and other objects orbit the sun inapproximately the same plane.
2) The planets and other objects orbit the sun in the same
direction.
3) The planets revolve around their axes in the same
direction as they orbit the sun.
4) The 4 inner planets (Mercury, Venus, Earth, and Mars)
are smaller and “rocky” than the 4 outer planets (Jupiter,
Saturn, Venus, & Neptune), which are large and gaseous.
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The most widely accepted hypothesis for the origin of the
Solar System is referred to as the Nebular HypothesisAccording to this theory, the solar system began as
a huge cloud of slowly rotating gas and dust,
known as a nebula.
Many nebulas are present in the universe and are
recognized as having resulted from the explosion of a
star. Slowly, the nebula that formed our Solar System
began to contract because of gravity
As the nebula contracted, it began to rotate faster. This
caused the cloud to flatten into a disk-like shape.
Most of the mass collapsed into the center.
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Eventually, the Sun developed in the center of the disk. The
sun was sufficiently massive that the process of nuclear fusion
began. Because of fusion, the Sun emits radiation (some of
which is light), along with charged particles - protons and
electrons.
This emanation of rapidly moving charged particles from theSun is known as the solar wind.
Collision of the solar wind particles with the particles away
from the sun blew the lighter elements, mostly hydrogen and
helium, in the disk away from the sun.
The heavier elements were too heavy to be blown outward.
Because most of the elements in the cloud orbiting the sun
were lighter (Hydrogen and Helium), most of the material thatwas closer to the Sun was blown outward.
In time, the particles orbiting the sun were attracted
to one another because of gravity and they began to
coalesce (come together). Eventually, the growing
bodies became the planets and other features of the
Solar System.
The heavier elements, which were closer to the Sun,
formed the 4 rocky inner planets, whereas the lighter
elements formed the 4 icy and gaseous outer planets.
How old is the Solar System?
There is strong evidence that the Solar System formed
4.5 billion years ago.
Scientists refer to this concept for the
origin of the solar system as the
Nebular Hypothesis
Artist depiction of early Earth forming from collisions
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Don’t confuse the “Nebular
Hypothesis” with the “Big Bang
Theory”
The Nebular Hypothesis explains the origin of the Solar
System
The “Big Bang Theory” explains the origin of the
Universe. Evidence indicates the universe began 13.7
billion years ago.
The universe includes everything that we know that exists. This
means not only our Sun, but all of the stars in the sky.