Transcript L1_Intro - Department of Earth and Planetary Sciences

Earth, Moon, and Mars:
How They Work
Professor Michael Wysession
Department of Earth and Planetary Sciences
Washington University, St. Louis, MO
Lecture 1: Introduction to the Universe
This Course
will focus on
Earth for the
first two days;
Mars and the
Moon on the
third (with lots
of the rest of
the solar
system
included all
along!).
2 Reasons:
#1: You can’t understand the geology of another planet
until you first understand the geology of Earth.
#1: You can’t understand the geology of another planet
until you first understand the geology of Earth.
(and one of these may one day be our home!)
#2: NASA plays a
major role in the
current scientific
investigation of
Earth
National Research Council’s Conceptual
Framework for New Science Education
Standards
Textbooks at college, high
school, middle school, and
elementary school levels
WWW.EARTHSCIENCELITERACY.ORG
Big Idea #1: Earth scientists use repeatable observations and
testable ideas to understand and explain our planet.
Big Idea #2: Earth is 4.6 billion years old.
Big Idea #3: Earth is a complex system of interacting rock, water, air
and life.
Big Idea #4: Earth continuously changing.
Big Idea #5: Earth is the water planet.
Big Idea #6: Life evolves on a dynamic Earth and continuously
modifies Earth.
Big Idea #7: Humans depend on Earth for resources.
Big Idea #8: Natural hazards pose risks to humans.
Big Idea #9: Humans significantly alter the Earth.
Where are these?
Where are these?
Venus
How do we know this?
Jupiter
Geosphere
Composition of Crust (%):
Weight
Oxygen 47.2
Silicon
28.2
Aluminum 8.2
Iron
5.1
Moles
61.7
21.0
6.4
1.9
Volume
93.8
0.9
0.5
0.4
Composition of Whole Earth
(weight %):
Iron
Oxygen
Silicon
Magnesium
Nickel
35
30
15
13
2.4
Hydrosphere: 96.5% in Oceans
3.5% in glaciers, groundwater
~0% in streams, lakes, atmosphere, biosphere
71% of Earth’s surface is covered with water.
If Earth were a perfect sphere, it would be covered with 2.25 km of water.
Atmosphere:
Composition:
N2 - 78.1%
O2 - 20.9%
Ar 0.93%
H2O - 0.1%
CO2 - 0.039%
(increasing)
Ne 0.0018%
Earth's magnetic field LOOKS LIKE there is a tilted, offset,
wandering, bar magnet in its core. (But there isn’t!!)
Fluid flow (convection) of liquid iron in Earth’s outer core
creates the magnetic field.  Magnetohydrodynamo
The magnetosphere protects us from
ionized particles of solar wind.
Biosphere: Extends from the seafloor and deep crust, to the tops of
mountains and the atmosphere.
3 - 300 million species; ~1.5 million identified
VERY significant geological agent (Ex: atmosphere, weathering)
Milky Way Galaxy
80,000 light years
across
(7.6 x 1017 km) =
760,000,000,000,000,000 km
…and the
universe is a
whole lot bigger
than this.
Three lines of evidence for the Big Bang:
1) Doppler shift of stars
2) Background microwave radiation
3) Composition of the universe
(Big Bang Nucleosynthesis – first 3-20 minutes)
Cosmic Microwave Background, un-enhanced (COBE
satellite)
Cosmic Microwave Background, variations enhanced
(WMAP – Wilkinson Microwave Anisotropy Probe satellite)
Milky Way
Andromeda
Milky Way
Nucleosynthesis:
1) Stellar nucleosynthesis – makes elements up to iron
during last stages of a star
2) Explosive nucleosynthesis – makes elements larger
than iron (from free neutrons) during supernovae of
large stars
Nucleosynthesis:
D + D  He
He + He  Be
Be + He  C
C + He  O
C + C  Mg
O + C  Si
(etc.)
Red Giant
Betelgeuse
Hourglass Nebula - collapsed white dwarf - gas ejected after
red giant phase
“Death” of
a star:
Helix Nebula - collision of two gas ejections from a dying star