Download Solar System Formation PPT

Introduction to
the Solar System
Grasping the size
 Scale of Solar SystemKhan Academy:
http://www.khanacadem
y.org/science/cosmology
-and-astronomy/v/scaleof-solar-system
 Astronomical Unit:
1 (AU) =
 149,597,870 km
 92,955,807 miles
 Beyond the Solar
System:
http://scaleofuniverse.co
m/
Survey of the Solar System
Lesson 15: Chap 4, Secs 4.2-4.3 Origin of the Solar System and Other Planetary Systems
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What’s our Motivation?
 Solar system is our “local
neighborhood”
 Want to get to know what’s
around you!
You
are
here
Survey of the Solar System
Lesson 15: Chap 4, Secs 4.2-4.3 Origin of the Solar System and Other Planetary Systems
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Lesson Overview
 How did the solar system form?
 What are interstellar clouds?
 What is a solar nebula?
 How did the solar nebula
evolve into the Sun and planets?
 Are other solar
systems out there?
Survey of the Solar System
Lesson 15: Chap 4, Secs 4.2-4.3 Origin of the Solar System and Other Planetary Systems
4
Introduction
 Two questions:
 How did the solar system form? and
 Are similar solar systems “out there”?
 There are various theories for how the
solar system formed
Survey of the Solar System
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How did the solar system form?
 Good theories must answer key questions:
 Why is the solar system flat?
 Why do all the planets orbit in the same direction?
 Why do two types of planets exist?
 Why do all solar-system bodies appear to be less
than 4.5 billion years old?
Survey of the Solar System
Lesson 15: Chap 4, Secs 4.2-4.3 Origin of the Solar System and Other Planetary Systems
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How did the solar system form?
 Current hypothesis for formation of Solar System:
Solar nebula hypothesis
 Proposes the solar system evolved from a rotating
mass of gas and dust (an INTERSTELLAR CLOUD)
 The interstellar cloud flattened into a disk.
 The outer part became the planets and the inner part
became the Sun.
QuickTime Movie: How
the solar system
formed
Survey of the Solar System
Lesson 15: Chap 4, Secs 4.2-4.3 Origin of the Solar System and Other Planetary Systems
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What are interstellar clouds?
 Beginning of solar system—
interstellar cloud
 Interstellar clouds—vast
collections of gases (mostly
Hydrogen)
 Interstellar cloud that formed our
solar system was probably
several light years in diameter
and 2 times the Sun’s mass.
Photograph of an interstellar cloud (the dark region at top), which
may be similar to the one that became our solar system. (Courtesy
Anglo-Australian Telescope Board, photo by David Malin.)
Survey of the Solar System
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What are interstellar clouds?
 Contain tiny dust particles called
interstellar grains
 Usually, contain elements like those
found in the Sun
Survey of the Solar System
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How did the solar system form?
 How do we get from an interstellar
cloud to our solar system?
 Solar nebula hypothesis
 Six steps to formation
Survey of the Solar System
Lesson 15: Chap 4, Secs 4.2-4.3 Origin of the Solar System and Other Planetary Systems
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Survey of the Solar System
Lesson 15: Chap 4, Secs 4.2-4.3 Origin of the Solar System and Other Planetary Systems
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Step 1
 Interstellar cloud starts
collapsing into a solar
nebula
 Occurs over several
million years
 Collapsed disk is called
the solar nebula
 Its bulge became the Sun;
disk became the planets.
Survey of the Solar System
Sketch illustrates
A. An interstellar cloud’s collapse
B. Its flattening
Lesson 15: Chap 4, Secs 4.2-4.3 Origin of the Solar System and Other Planetary Systems
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What is a solar nebula?
 Before planets formed—inner part of
disk was hot, outer disk was cold.
A
B
A. The small blobs in this picture are protostars in the Orion nebula—a huge
gas cloud about 1,500 light years from Earth. (Courtesy Space Telescope
Science Institute.)
B. Picture in false color of a disk of dust around the young star, b Pictoris,
made at the ESO telescope. Dark circle blots out the star's direct light,
which would otherwise overexpose the image. (Courtesy A. M. Lagrange,
D. Mouillet, and J. L. Beuzit, Grenoble Observatory)
Survey of the Solar System
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Survey of the Solar System
Lesson 15: Chap 4, Secs 4.2-4.3 Origin of the Solar System and Other Planetary Systems
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Step 2:
How did the solar nebula evolve
into the Sun and planets?
 Basic elements in the solar
nebula condensed into small
particles. (Hydrogen, Iron,
Water vapor, Silicon)
On a hot day, water
vapor from the air
condenses on a
cold glass of water,
making a messy
puddle if you don’t
have a coaster.
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How did the solar nebula evolve
into the Sun and planets? (cont’d)
 Step 2 (from previous): Basic elements in the solar nebula
condensed into small particles.
 Materials condensed at different temperatures:
At colder
temperatures . . .
Iron vapor condensed and
became a solid at 1300 K.
Silicate vapor condensed and
became a solid at 1200 K.
Water vapor condensed and
became solid ice at 273 K.
Hydrogen vapor condensed
and became solid at 14 K.
Survey of the Solar System
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How did the solar nebula evolve
into the Sun and planets?
 Step 3: Small particles gradually formed
larger particles through accretion (sticking
together).
 Step 4: Over time, the larger particles
collided and stuck together to form
planetesimals.
 Step 5: Over more time, planetesimals
gently collided to form the planets.
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How did the solar nebula evolve
into the Sun and planets? (cont’d)
 Step 3: Accretion
 Step 4: Forming planetesimals
 Step 5: Planetesimals forming planets
Sketches
showing (A) how
dust grains may
have grown into
planetesimals
and (B) how the
planetesimals
may have grown
into planets.
Survey of the Solar System
Lesson 15: Chap 4, Secs 4.2-4.3 Origin of the Solar System and Other Planetary Systems
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How did the solar nebula evolve
into the Sun and planets? (cont’d)
Sketches
showing (A) how
dust grains may
have grown into
planetesimals
and (B) how the
planetesimals
may have grown
into planets.
Survey of the Solar System
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Survey of the Solar System
Lesson 15: Chap 4, Secs 4.2-4.3 Origin of the Solar System and Other Planetary Systems
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How did the solar nebula evolve into
the Sun and planets? (cont’d)
 Step 6: Planetary atmospheres formed.
 Outer planets were big enough so their
gravity could capture lighter gases to form
atmospheres.
 Inner planets created atmospheres by
volcanic activity and perhaps from comets
and asteroids that vaporized.
 Some planets were too small to keep
gases on their surface
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Survey of the Solar System
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Are there other solar systems out there?
Survey of the Solar System
Lesson 15: Chap 4, Secs 4.2-4.3 Origin of the Solar System and Other Planetary Systems
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Are there other solar systems out there?
Survey of the Solar System
Lesson 15: Chap 4, Secs 4.2-4.3 Origin of the Solar System and Other Planetary Systems
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Are there other solar systems out there?
Survey of the Solar System
Lesson 15: Chap 4, Secs 4.2-4.3 Origin of the Solar System and Other Planetary Systems
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Lesson review
 How did the solar system form?
 A currently favored theory for the solar system’s origin is
the solar nebula hypothesis. Six steps:
 Step 1: An interstellar cloud collapsed to form a solar nebula.
 Step 2: Basic elements condensed into small particles.
 Step 3: Small particles gradually formed larger particles through
accretion.
 Step 4: Larger particles collided and formed planetesimals.
 Step 5: Planetesimals gently collided to form the planets.
 Step 6: Planetary atmospheres formed.
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Activity—Questions for review
 What is the currently favored theory for the solar
system’s origin called?
 What are the six steps that formed the solar system?
 What is an interstellar cloud?
 What is a solar nebula?
 What is accretion?
 What are planetesimals?
 *What size planets have we found around other stars?
Survey of the Solar System
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Activity—Test yourself
• The solar nebula hypothesis proposes that _______ ________
evolved from a rotating, mass of gas and dust (called an
interstellar cloud).
• *Interstellar clouds are vast collections of gases that contain about
___% hydrogen, ___% helium, and traces of the other elements.*
• Basic elements (hydrogen, iron, etc.) in the solar nebula _______
into small particles.
• Small particles in the solar nebula gradually formed larger
particles through _________.
• Over time, the larger particles in the solar nebula collided and
stuck together to form __________ .
• Planets formed from _______ ________ of the planetesimals.
• *New planets found around other stars aren’t observed directly.
Instead, we see their ________ ________ on their parent stars.*
Survey of the Solar System
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