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Planetary Geology
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Origin and early history of the universe
Changing composition of the universe
Origin and history of the solar system
Origin and differentiation of early earth
The origin and early history of the
universe
• Big Bang
• Four basic forces:
Gravity, electromagnetic force, strong
nuclear force, and weak nuclear force
These forces are responsible for all
interactions of matter.
Early History of the Universe
• Big Bang – the origin of the universe;
Astrophysicists can reconstruct the history
back to 10-43 seconds following the Big
Bang
• Most suspect that at the extreme
temperatures just before 10-43 seconds,
the four basic forces were united into a
single unified force
At
-43
10
seconds after Big Bang
• Physics, as we know it, starts here
• Gravity separates from the other basic
forces
• Temperature estimated to be 1032 K
• Expanding universe believed to be only
10-28 centimeters in diameter
At 10-35 to 10-32 seconds after
• Major inflationary period takes place
• The strong force separates
• Energy begins to congeal into quarks and
electrons and their mirror images,
antimatter
• Temperature cooled to 1027 K
• Expanded to size of a softball
At 10-6 seconds after Big Bang
• Cooled enough (1013 K) so that quarks
bind into protons and neutrons
• Matter and antimatter collide and
annihilate each other
• Asymmetrical universe allows for a slight
excess of matter left over
• Left over matter becomes our present
universe of galaxies, stars, and planets
At one second after Big Bang
• Electromagnetic and weak nuclear forces
separate
Three minutes after Big Bang
• Temperature cooled to 109 K
• Protons and neutrons fuse to form the
nuclei of hydrogen and helium atoms
At 105 years after Big Bang
• Temperature cooled to 3000 K
• Electrons combined with nuclei to create
complete atoms of hydrogen and helium
• Photons (energetic particles of light)
separate from matter, and universe bursts
forth with light (This liberation of photons
is what we observe today as the 3K
background radiation permeating the
universe)
105 to 109 Years after Big Bang
• Universe becomes “clumpy”
• Matter began gathering into clouds of
different sizes
• Clouds eventually collapsed to form
clusters of galaxies and stars
• Galaxies tend to form like beads on a
string into superclusters, the largest
celestial objects known
Galaxies
Stars
Solar System - Observations
1. All planets revolve around the sun in the same
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direction; this direction is the same as the
rotation of the sun.
The orbits around the sun are nearly circular.
All planetary orbits except that of Pluto lie in a
common plane, called the plane of the
ecliptic.
Planet comparison
Solar System observations cont.
4. All of the planets except Uranus and
Pluto have axes of rotation that are
nearly perpendicular to the plane of the
ecliptic.
5. The 4 innermost planets all have similar
densities and compositions.
6. The 4 outer planets that are gas giants
have similar densities and compositions.
Planet comparisons
Solar System observations cont.
7. All planets except Venus and Uranus and
most of the planetary moons rotate in a
counterclockwise direction.
8. There is an asteroid belt between Mars
and Jupiter.
Solar System
ANTARES IS THE 15 TH BRIGHTEST STAR IN THE SKY.
IT IS MORE THAN 1000 LIGHT YEARS AWAY.
The View From Space: A
group of new born stars
occurs in a cluster 12
billion light years from
Earth, as viewed by the
Hubble Space Telescope.
The light from the stars
makes the gas and dust
surrounding them glow.
Our solar system may
have formed from such
a cloud.
Solar Nebula Theory
• ~ 4.6 bya a cloud (nebula) of interstellar
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material (mostly H and He) within a spiral arm of
the milky way galaxy began to contract and
flatten into a rotating disk
Disk rotated and most of the mass concentrated
in the center
Surrounding the central disk, the turbulent
rotating nebula of interstellar gases began to
cool and condense, forming solid particles
Solar Nebula Theory
• Massive central disk formed a star, our sun
• Sun began to emit electromagnetic
radiation
• Solid particles in the nebula collided and
accreted (stuck together), becoming larger
and more massive forming
planetesimals
• As more and more particles accreted, the
planetesimals formed planets
Understand meteorites and the age
of the earth
Meteorites
• Believed to be examples of the original
material from the solar nebula.
• Used to learn about the origins of our
solar system and the planets
Assignment
• Lab # 7 “Astronomy” page 107
• Homework: Read Ch 8 “Earliest Earth”
(Page 207 – second half of textbook)
• Answer questions # 2, 3, 6, 14, & 15
(page 240/241) – DUE next class