ORIGINSOceans & Continents

CrustEarth

Solar SystemUniverse

The Universe

• Planets• Stars• Galaxies• Clouds of Dust & Gas• Interstellar Space

Clouds of dust and gas in Eagle Nebula (Hubble Picture)

View of Galaxies in deep space from Hubble space telescope

Sombrero Galaxy

Andromeda Galaxy

Milky Way Galaxy

Scientific Method

• Observations or experiments• Hypotheses• Testing• Theories (Scientific Truths)

Origin of Universe

• Evidence• All galaxies in universe appear to be

moving away from one another (Red Shift in Starlight)

• The greater their distance the faster they are receding

• The temperature of interstellar space is not 0o K but 2.7o K

• Big Bang Theory

Origin of Solar System

• Evidence• Astronomical observations of stars beyond

solar system• Observations of structure

& composition of solar system• Internal structure and composition of Earth

Star Formation in a Dust and Gas Cloud in Scorpius

Sun during eclipse

Solar Spectrum

The Sun

• Sun makes up 99.9% of Solar System• Sun is mainly made of:

• Hydrogen (element #1, simplest and most abundant element in universe)

• Helium (element #2, second most abundant)

• Solar energy produced by nuclear fusion• 4 Hydrogen nuclei = 2 Helium nuclei +

energy

The Solar System

• With exception of Pluto, all planets occupy sub-circular orbits

• All orbit in the same plane (ecliptic) and in same direction

• Nearly all rotate in same direction about axes that are nearly perpendicular to ecliptic

The Planets

Inner Planets• Mercury, Venus,

Earth, Mars• Small, dense,

rocky. • Few moons

Outer Planets• Jupiter, Saturn,

Uranus, Neptune• Large, low

density, icy.• Many moons• Pluto

Solar System and Outer Planets

Internal structure of Earth

• Atmosphere <1 g/cm3

• Hydrosphere 1 g/cm3

• Crust 2.7-2.9 g/cm3

• Mantle 3.3-5.6 g/cm3

• Core 10-14 g/cm3

A Differentiated Planet

Nebular Theory

• Star systems are formed by the gravitational collapse of diffuse clouds of dust and gas (nebulae)

• Cold clouds of dust and gas (mainly hydrogen) are most abundant constituents of universe

• Gravitational collapse always leads to rising temperatures.

Planet Earth

• Rising temperatures lead to partial melting

• Light melting fractions rise• Heavy melting fractions sink• Result - a layered structure with

core, mantle, crust, ocean and atmosphere

Crust– Two Types

• BASALTIC CRUST 2.9 g/cm3 (3-5mls thick) Iron, magnesium, silica rock (mafic rock)

• GRANITIC CRUST 2.7 g/cm3 (10-40mls thick) Aluminum, silica rock (felsic rock)

Crust rigid and brittle generates earthquakes

Isostacy

The floating balance that exists between dense plastic mantle and

light brittle crust

Elevation of Earth’s Surface

CompositionDensity

Temperature

Thickness