The Origin of the Solar System

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The Origin of the Solar System
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Planetary Orbits
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The Sun is the center of our solar system.
All planets in almost circular (elliptical)
orbits around the sun, in approx. the same plane
(ecliptic).
Mercury
Solar system made up of 8 planets, 169 moons,
asteroids comets, dust and gas
Venus
Sense of revolution counter-clockwise
Mars
Jupiter
Earth
Sense of rotation counter-clockwise (with
exception of Venus, Uranus, and Pluto)
Uranus
Saturn
Neptune
(Distances and times reproduced to scale)
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The Solar Nebula Hypothesis
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Basis of modern theory of planet formation.
As cloud continued to fall to center it got so
hot that nuclear fusion was initiated and a star
was born
T Tauri occurred, the sun turned on and blew most
of the gas dust in the new solar system.
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The Age of the Solar System
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Sun and planets should have about the same age.
Ages of rocks can be measured through radioactive
dating
Measure abundance of a radioactively decaying
element to find the time since formation of the
rock
Dating of rocks on Earth, on the Moon, and
meteorites all give ages of 4.6 billion years.
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Supernova

• Huge explosion of a star.
• Caused by the core of the star collapsing in less
  that a second
• Last 1 to 2 years
• 2 things formed
• Neutron star
• Black hole

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The Story of Planet Building
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Planets formed from the same protostellar
material as the sun, still found in the Suns
atmosphere.
Rocky planet material formed from clumping
together of dust grains in the protostellar cloud.
Mass of more than 15 Earth masses
Mass of less than 15 Earth masses
Planets can grow by gravitationally attracting
material from the protostellar cloud
Planets can not grow by gravitational collapse
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The Growth of Protoplanets
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Simplest form of planet growth
Unchanged composition of accreted matter over time
As rocks melted, heavier elements sink to the
center ? differentiation
This also produces a secondary atmosphere ?
outgassing
Improvement of this scenario Gradual change of
grain composition due to cooling of nebula and
storing of heat from potential energy
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Two Kinds of Planets
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Planets of our solar system can be divided into
two very different kinds
Terrestrial (earthlike) planets Rocky
composition Mercury, Venus, Earth, Mars
Jovian (Jupiter-like) planets Icy composition
Jupiter, Saturn, Uranus, Neptune
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What will happen to solar system?

• It is a middle aged star
• In 5 billion years

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Terrestrial Planets
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Four inner planets of the solar system
Relatively small in size and mass (Earth is the
largest and most massive)
Rocky surface
Surface of Venus can not be seen directly from
Earth because of its dense cloud cover.
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Craters on Planets Surfaces
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Craters (like on our Moons surface) are common
throughout the Solar System.
Not seen on Jovian planets because they dont
have a solid surface.