Open Earth Systems: An
Earth Science Course
For Maryland Teacher
Professional Development
EARTH HISTORY AND THE FOSSIL RECORD
DAY 1 - Weds. July 8
AM Instruction: Solar System Origin
Activity 1: Period of planetary orbits
Activity 2: Planets on your birthday
Instruction: Early Earth & Habitability
-lunchtimePM Instruction: Major Events in Earth History
Activity 3: Exploring Geologic Time with TS-Creator
Instruction: Concepts in Radioisotope-dating
Activity 4: Simulating Radioactive Decay
DAY 2 - Thurs. July 9
AM Instruction: Climates of the Past
Activity 5: JHU Soil Profile
Instruction: Fossil Record of Life
-lunchtimePM Instruction: Conversation with Steven Stanley
Activity 6: Fossil Identification
LINDA HINNOV, Instructor
OUTLINE
• Origin of Solar System
• The Planets
• Meteorites
Origin of Solar System
• Our Solar System formed about 5 billion years ago.
• The Sun (and other stars) formed from a nebula, a cloud of dust and
hydrogen gas.
• Stellar nurseries are abundant in spiral galaxy arms (e.g., the Milky Way).
• A slowly rotating globule formed due to gravitational forces
Age of Solar System
is inferred from
radioisotope dating
of meteorites and
Earth rocks.
Origin of Solar System
• The globule cooled through emission of radio waves and infrared radiation.
• It was compressed by gravitational forces and shock waves from supernovae
or hot gas released from nearby bright stars.
• These forces caused the globule to collapse and rotate faster.
• The collapse took 10,000 to 1,000,000 years.
A shock wave from
an exploding
massive star
(supernova) several
light-years away
probably triggered
the collapse of the
molecular cloud
(globule) that would
become our sun and
planets.
Origin of Solar System
Central core and protoplanetary disk: As collapse proceeded,
temperature and pressure in the globule increased. The globule rotated
faster and faster, increasing centrifugal forces and causing the globule to
develop a central core and a surrounding flattened disk of dust
(protoplanetary disk or accretion disk). The central core became the star;
the protoplanetary disk coalesced into orbiting planets, asteroids, etc.
Origin of Solar System
Protostar: The contracting cloud heats up due to friction and forms a glowing
protostar for ~50 million years.
Newborn star and Solar System: When a temperature of 27,000,000°F is
reached, nuclear fusion begins in the new Sun’s core, reaction in which
hydrogen atoms are converted to helium atoms plus energy. This energy
production prevents further contraction of the Sun.
Origin of Solar System
Young stars emit radiation jets that heat surrounding matter to the point at
which it glows brightly. Jets can be trillions of miles long and travel 500,000
miles per hour. The Sun later stabilizes and becomes a yellow dwarf, a main
sequence star which will remain in this state for 10 billion years. After that, the
hydrogen fuel is depleted and the Sun begins to die.
Origin of Solar System
Our Solar System is located in the outer Milky Way
Galaxy, a spiral galaxy with 200 billion stars, most
not visible from Earth. Almost everything that we
can see in the sky is in the Milky Way Galaxy.
The Sun is 26,000 light-years from the center of the
Milky Way Galaxy,
The Milky Way Galaxy is 80,000 to 120,000 lightyears across and <7,000 light-years thick.
We are located on one of its spiral arms, near the
edge.
From Earth, our Milky Way
Galaxy is visible as a
milky band that stretches
across the night sky.
It takes the Sun (and our Solar System) 200-250
million years to orbit once around the Milky Way.
In this orbit, we (and the rest of the Solar System)
are traveling at a velocity of about 155 miles/sec
(250 km/sec).
SUMMARY
CLICKER Question
QUESTION: Our Sun began emitting light:
a) when gravitational collapse occurred
b) nuclear fusion reactions began
c) with rotation of the nebula
d) with a supernova explosion
e) when Moon collided with Earth
The Planets
The Planets
The Planets
CLICKER Question
QUESTION: Which other planet has a near-Earth day?
a) Jupiter
b) Venus
c) Mars
d) Mercury
e) Pluto
Meteorites
Geologic inventory of major impacts
IMPACT SITES
Barringer Meteor Crater, AZ.
35°02'N, 111°01'W; diameter: 1.186
kilometers (.737 miles); age: 49,000
years.
Chicxulub, Yucatan, Mexico
N 21° 20’, W 89° 30'
170 km diameter
64.98 ± 0.05 million years
asteroid – A big rock or aggregation of rocks orbiting the Sun
meteoroid – A small rock orbiting the Sun
meteor – The visible light that occurs when a meteoroid
passes through the Earth’s atmosphere
meteorite – A rock existing on Earth that was once a meteoroid
http://www.britannica.com/eb/art-89387
http://www.amnh.org/rose/meteorite.html
http://solarsystem.nasa.gov/multimedia/gallery/Chicxulub-browse.jpg
Meteorites
Types of meteorites
5%
Iron meteorites are composed of iron
metal with 5 - 20 wt. % nickel. They are
sub-divided into different groups on
the basis of trace element chemistry.
They are sub-divided by
metallographic texture.
1%
Stony-iron meteorites have equal
proportions of silicate minerals and
iron-nickel metal. They are sub-divided
into two major groups, mesosiderites
and pallasites, which have very
different origins.
94%
Stony meteorites are made from the
same elements as Earth rocks: Si, O,
Fe, Mg, Ca and Al. Like Earth rocks,
stony meteorites are assemblages of
minerals: pyroxene, olivine and
plagioclase, but unlike Earth rocks,
they also contain metal and sulfides.
http://www.nhm.ac.uk/jdsml/research-curation/projects/metcat/bgmettypes.dsml
http://piclib.nhm.ac.uk/meteorite-blog/image.php?src=http://www.nhm.ac.uk/nature-online/space/meteorites-dust/images/types-l.jpg&from=/meteorite-blog/
Meteorites
Origins of meteorites
1. ASTEROIDAL
99.99% percent of all meteorites are of
asteroidal origin.
STONY:
Enstatite -- (inner asteroid belt)
Ordinary -- (middle asteroid belt)
Carbonaceous -- (outer asteroid belt)
IRON:
Originate from M-type asteroids, and
are thought to be core fragments of
large asteroids shattered by impacts.
Meteorites
Origins of meteorites
2. LUNAR
Chemical compositions, isotope ratios,
minerals, and textures of the lunar meteorites
are all similar to those of samples collected
on the Moon during the Apollo missions. These
characteristics are different from those of any
other type of meteorite or Earth rock. For
example, all of the meteorites that are
classified as feldspathic breccias are rich in
anorthite (plagioclase feldspar), with high
concentrations of aluminum and calcium.
Uniquely, the lunar highlands are composed
predominantly of anorthite. Anorthite is much
less common in asteroids or on the surface of
any other planet or moon.
3. MARTIAN
Of the 24,000 or so meteorites that have
been discovered on Earth, only 34 have
been identified as originating from the
planet Mars. These meteorites are divided
into three rare groups of stony meteorites:
shergottites (25), nakhlites (7), and
chassignites (2). Consequently, Mars
meteorites as a whole are sometimes
referred to as the SNC group. They have
isotope ratios that are consistent with
each other and inconsistent with the Earth.
They are young: 1.3 Ga.
CLICKER Question
QUESTION: Lunar and Martian meteorites are:
a) nickel
b) pallasites
c) iron
d) eclogitic
e) stony