Geology Exam 3 notes

Geology Exam 3 notes - Chapter 9: Early history of the...

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Chapter 9: Early history of the terrestrial planets 1. Origin of the solar system The nebular hypothesis o Immanuel Kant suggested that the origin of the solar system could be traced to a rotating cloud of gas & fine dust – now referred to as nebular hypothesis o The 2 gases that form these clouds are hydrogen & helium The sun forms o Under the pull of the gravity, material began to drift toward the center, accumulating into a protostar. The planet forms o Solar Nebula a disk of gas & dust o Planetesimals – gravitational attraction caused the dust & condensing material to clump together in “sticky” collisions as small chunks called planetesimals o Inner planets –4 inner planets in order of closeness to the sun are : Mercury, Venus, Earth, Mars Also knows as Terrestrial “earthlike” planets Small & made up of rocks (rock forming silicates) o Outer planets – giant outer planets made up of mostly ices & gases are: Jupiter, Saturn, Uranus, & Neptune Composed mostly of hydrogen & helium Solar system started as a spinning contracting nebulous (cloud of dense matter), b/c it’s not new, it starts to spin, & therefore it builds up & pulls its mass toward the center; the cloud continues spinning & flattens into a disk; the enveloping disk of gas & dust forms grains that collide & dump together into small planetesimals (chunks) - little beginning of planets; starts to build up & planetesimals get bigger; eventually the sun is established in the center & other planets establishing themselves at a distance from the sun Outer plants – mostly made of gas (referred to as gas giants) Origin of the solar system Small bodied of the solar system o Asteroids o Meteorites – strike the earth, pieces of asteroids ejected during collisions w/ 1 another Asteroids Asteroid belt – represent particular distance from the sun Relatively close to Jupiter & therefore doesn’t form into a planet b/c Jupiter is so large & has so much gravitational force associated w/ it Early earth: forming a layered planet: Differentiation- transformation into a layered planet Earth heats up & melts o The magma ocean – surface of the earth o Impact formation of the moon - formation of moon due to an impact of a giant body o About 4.5 billion years ago, a Mars-sized body impacted the earth o Tore the earth apart quite a bit – a lot of stuff was blown away from the initial earth & all of the pieces started to spin around the earth o The impact sped up earth’s rotation & tilted earth’s orbital plane 23 degrees o Eventually all the material continued orbiting the earth , accumulated & formed the moon Planets closer to the sun are the most dense Planets further away from the sun are least dense Moon has a fairly low density After the impact - Earth’s core, mantle, & crust forms Earth’s oceans & the atmosphere forms
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Geology Exam 3 notes - Chapter 9: Early history of the...

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