A review of:

~14 Billion years agoDense, hot, tiny,

massive point in spaceExplodedUniverse expanded to its

current state, and is still expanding due to the force of that explosion. It is also still cooling from

this hot, violent eruption.

First few seconds all matter was created Atoms could not form at first since it was

TOO hot. Particles were all moving too fast

Cooling led to the formation of atoms / molecules within 300,000 years after the Big Bang

Only formed Hydrogen, small amounts of Helium. All Hydrogen of the universe was formed at

that time.

1 Billion years later…Formed in areas where there were

large amounts of interstellar matter Dust and Gas

Temperature needs to be high enough for FUSION to occur. Side Note: Fusion

▪ E=mc2

▪ 4H→1He + ENERGY▪ Continues to form heavier elements

Large stars can produce heavier elements Eventually the stars EXPLODE (more on

this later) in a supernova All of the elements created were

RELEASED into space Responsible for the formation of all

elements in the periodic table Our sun has traces of heavy elements in

it, thus it must be AT LEAST a 2nd generation

Formed ~ 10 billion years ago

Spiral galaxy Cluster of stars, matter,

and other celestial objects that are gravitationally bound and rotate around the center of a massive black hole.

Nebular Theory Rotating disk of dust

and gas Hottest at the center

(what formed here??) Formed on one of the

spiral arms of the galaxy IMPORTANT! (more on this later)

~5 billion years ago Eight planets formed

Inner (Rocky) planets Outer (Jovian / Gaseous) planets

Formed 4.6 billion years ago

Middle of solar system Densest collection of

matter Hottest temperatures

Collection of gas / dust that contracted until fusion began (more on this later)

T-tauri phase 4.5 billion years ago (IMPORTANT!)

“shedding” phase Particles swept out by solar

wind to furthest parts of the solar system

Which would travel further – lighter particles, or heavier particles?

Take a look at the periodic table – which particles would be lighter?

The T-tauri phase determined the composition of the 8 planets

http://upload.wikimedia.org/wikipedia/commons/8/8e/Hs-2000-32-a-animated_gif.gif

Reached current size 4.4 billion years ago Mercury, Venus, Earth, Mars Similar compositions, structures

All have a core, mantle, and crust region (the structure of the Earth will be covered in more detail in a later unit)

High density Rocky, metallic, heavier elements Smaller

Formed from planetary accretion, planetesimals

Reached current size 4.4 billion years ago Jupiter, Saturn, Uranus, Neptune Gaseous Giants / Jovian Planets Similar composition / structure

Possibly rocky / solid cores? Lighter, gaseous elements Largely composed of H & He, especially their atmospheres

(which also accounts for most mass in the solar system) – would that be expected?

Properties of the planets / solar system will be discussed in the next unit

Earth’s moon formed 50,o00 years after Earth COLLISION THEORY for formation Evidence:

Identical compositions More details on the moon next unit!

Earth’s core formed 4.35 billion years ago Kinetic energy from accretion

→ heat energy Radioactive decay →heat energy

▪ An aside on radioactive decay (discussed further later)……▪ What is it?

▪ Earth’s internal heat energy source!

▪ Leads to a lot of volcanism (which in itself is important because it renews the land / soil / nutrients) Atmosphere becomes rich in CO2 and H2O

Earth becomes molten!▪ Heavier elements: sink (Iron and Nickel)

▪ Created a magnetic field around Earth that protected us from the Sun’s harmful rays, and other high energy particles from space, which protects life.

▪ Aurora belts / Northern Lights

▪ Lighter elements: float to the top (Nitrogen, Carbon)▪ These elements are ESSENTIAL for life, so this process

was CRUCIAL in the development of life on Earth!!

Early Atmosphere (4.4-4.0 bya)▪ Light elements (H, He, methane), H2O and others

▪ Lightest elements escaped to space

Secondary Atmosphere (4.0-3.3 bya)▪ Dominated by gases released in volcanic eruptions (CO2,

H2O, N2)▪ Condensation (due to cooler temperatures)leads to most

H2O precipitating out to form oceans

Primary Atmosphere (3.3 bya - present)▪ Evolution of life / plants leads to photosynthesis

▪ Atmosphere becomes rich in O2, less CO2 (some fluctuations through the years)

Evolution of Earth’s Atmosphere

Believed to have formed from: Continued rain (so much water vapor in the

atmosphere from all of the volcanic activity lead to a lot of condensation!)

Impacts of icy meteors / comets, whose water melted.

Not entirely sure, however. Oceans harbored and fostered life. The

first advanced life forms developed in the ocean. Eventually, life made the leap from ocean to land, but we can thank the oceans for allowing us safe haven while the land was going through such a chaotic time!

All molten at first Due to frequent volcanic eruptions, land

was constantly being renewed; surface was constantly changing▪ Rapid changing environment and climate led to

mass extinction and the birth of many new species in short periods of time

Oldest rock known on Earth formed 3.8 bya Stable continents first formed 2.5 bya

▪ NOT Pangaea (200 mya) -Gondwana & Laurasia; formation of Appalachian Mountains

Land on Earth

Bacteria developed 3.9 – 3.5 billion years ago (not sure how)

Development of plant life is CRUCIAL – why? Photosynthesis!

▪ Turns CO2 into O2! ▪ Developed oxygen rich atmosphere (~20%) 3 billion years

ago▪ Allows life to exist on Earth!!

Extinction of dinosaurs from impact 65 mya Mammals survive, and leads to our evolution

and domination! Otherwise, the reptiles might still be in charge!!

1st humans appear 200,000 years ago

Hadean (Earth forms - 3.8 bya)▪ Atmosphere evolves, oceans begin to form

Archean (3.8-2.5 bya)▪ Life develops, O2 rich atmosphere develops▪ Oldest known solid rock develops

Proterzoic (2.5 bya - 542 mya)▪ Stable continents appear

Phanerozoic (542 mya - present)▪ Multicellular life evolves, life moves onto land from the

sea Precambrian - 1st 3 eons, before multicellular life

Earth’s Eons