History of the Earth Chapter 1: Formation

of the Earth

From the Big Bang to Early Planets

Origins of…• The Universe (13.7 Gyr)

• The Elements (13.7 - 4.6 Gyr)• The Solar System & the Earth (4.6 Gyr)

• The Moon (4.5-4.6 Gyr)

Hubble Deep Field

Origin of the Universe (13.7 Gyr)

TheBig Bang

WMAPWilkinson Microwave Anisotrophy

Probe

Microwave light emitted 380,000 yrs after the Big Bang

History of the Universe

Stars Begin to Form about 300,000 years after the Big Bang

At that time Universe is:• 75% Hydrogen• 25% Helium

What about the rest of the elements?

Nebula

How a Star Works

RadiationPressure

Gravity

Nucleosynthesis

Stellar Death: Collapse

RadiationPressure

Gravity

Supernova: Crab Nebula

Supernova Remnants

Eagle Nebul

a

Origin of the Elements

• Hydrogen & Helium: Big Bang

• Helium to Iron: Stellar Fusion Multiples of 4 most common:

Helium Carbon, Oxygen, Neon, Magnesium, Silicon, Sulfur, Iron

• Iron to Uranium: Supernova

Origin of the Solar System:The Data

1. 99% of the mass of the solar system is in

the sun

2. We know thecomposition of the sun

3. Planets orbit the sun in the plane of the sun’s equator

4. Planets come in two groups:

Terrestrial Planets

Mercury Venus Earth Mars

- Small, Dense and made of Rock and Iron

4. Planets come in two groups:

Jovian Planets

Jupiter Saturn

Uranus Neptune

- Large, Low Density, and Made of Gas and Ice

Asteroids

Mathilde & Eros (NEAR)

Ida & Dactyl

Kuiper Belt & Pluto

5. Meteorites

Chondrites

Carbonaceous

Ordinary

Chondrules under a scope

X-Ray Image

Abundance of Elements

in Carbonaceou

s Chondrites

Achondrite - Stony Meterorite

A stone from the Stannern eucrite showerthat fell over Moravia, Czech Republic in 1808.

Iron Meteorit

e

Stony-Iron:

PalasiteOlivine

Iron

6. Properties of the Earth

Origin of the Solar System:InterpretationSolar Nebula Hypothesis

1. Start With a Nebula

Something (Supernova

?) Triggers Nebula to Collapse

2. Nebula Collapses to form Protostar (Early

Sun)

Protostar Formation

3. Residual Material Begins to Cool and

Accrete

3a. “Gas” Segregated by Melting Temperature

and Condenses

3b. Accretion: Dust Particles Accrete into

Planetesimals

3b. Planetesimals Accrete into Planets

DaDa! - A Solar System

Dust Disks Around Young Stars

Extrasolar

Planets

First Extra-Solar Planet

Photographed

(2005)

4. Terrestrial Planets Heat

up and Differentiat

e:Iron

CatastropheHeat Comes From:1. Kinetic Energy of Accretion2. Gravitational Energy3. Radioactive Decay4. Differentiation

Earth’s

Interior

Meteorite Sources

Meteorites & Solar System Age

•Formation: 4.56 billion yearsMeteorites all with 20 myrs(earliest within few Myrs of supernova)

•Supernova to sun and planetesimals - few million years! •Layered earth about 96±12 Myrs after meteorites•Nebula to layered earth & moon - about 100 Myrs

Earth in the Early Hadean?

2004 - Fred Sulahria