Earth, Moon, and Mars: How They Work

Professor Michael WysessionDepartment 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 Jupiter

How do we know this?

Composition of Crust (%):Weight Moles Volume

Oxygen 47.2 61.7 93.8Silicon 28.2 21.0 0.9Aluminum 8.2 6.4 0.5Iron 5.1 1.9 0.4

Composition of Whole Earth (weight %):Iron 35Oxygen 30Silicon 15Magnesium 13Nickel 2.4

Geosphere

Hydrosphere: 96.5% in Oceans3.5% 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

Process of nuclear fusion within stars (fusing hydrogen into helium)

Nuclear Fusion: Many possible reactions

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