origins oceans & continents crust earth solar system universe
TRANSCRIPT
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