EPS 101 Spring 2001 – Adrian Brearley - Lecture 2

Building a Planet – Formation of the Solar System

IRAS image of planetary disk around

the star Beta Pictoris

Keywords and concepts

General

Geology – science of study of the Earth, how it formed, how it changed or evolved through geological time.

Geologic time – Scientific evidence argues that the Earth and other planetary bodies in the solar system are extremely old – 4.5 b.y. Geological processes both fast and slow have operated over this immense period of time to shape the Earth.

Scientific method – hypothesis, theory

Principle of Uniformitarianism – Present is the key to the past.

Origin of the Solar System

Origin of Solar System – Big Bang – 10 to 15 b.y, ago – formation of Universe – galaxies – birth place of stars – Milky Way galaxy – home to our solar system.

Nebular hypothesis for formation of solar system – collapse of cloud of interstellar dust and gas. Formation of protosun, protoplanetary disk.

Planetary accretion – progressive accretion (sticking together) of dust into larger and larger objects by gravitational attraction – eventual formation of planetary sized objects.

Inner terrestrial planets – Mercury, Venus, Mars, Earth

Outer Gaseous Planets – Jupiter, Saturn, Uranus, Neptune, Pluto and their satellites and moons.

Meteorites – From Asteroid belt – material that did not accrete into planets – unprocessed since time of formation – crucial information about the types of materials that came together to form planets.

Early Evolution of the Earth

Planetary Differentiation – process of conversion of nebular (meteoritic) materials into a planet with a core, mantle and crust.

Heavy Bombardment – period of cataclysmic impacts in early solar system history that affected all planets in the solar system. Possible significant heating mechanism.