Formation of the Solar System

MODELS OF THE SOLAR SYSTEM There are two main models that have existed in history ________________________________________________________ Also called the Ptolemy Model Also called the Copernican Model

Model with Earth in the ______________________________ GEOCENTRIC MODEL Model with Earth in the ______________________________ Everything in space revolved around the ________________ Proposed by many including the famous Greek philosopher, Aristotle, around 350 BC In 140 AD, ________________________ expanded Geocentric Model Could _____________________________________ motion of the sun and planets Used mathematics and little observation Very complicated Used for over 1000 years

Think! What did Aristotle propose about the Solar System? Define ‘geocentric’:

HELIOCENTRIC MODEL Model with ______________ in the center of the Solar System In 1543, Nicolaus Copernicus moved the sun to the center. Was ___________________________by scientific community

DEVELOPMENT OF THE HELIOCENTRIC MODEL In 1605, Johannes Kepler improved the model by proposing that the orbits around the sun are ______________________, or ovals, rather than circles. In 1609, Galileo Galilei made a ________________________ Key ___________________________________ that allowed important __________________________________ to be made in support of the Heliocentric Model In 1687, Sir Isaac Newton ties it all together Explained that ___________________________________ keeps the planets in orbit around the sun, and satellites in orbit around planets.

Think! What did each of these scientists do or say to build on our knowledge of the Solar System: Copernicus? Kepler? Newton?

STEPS THAT LEAD TO THE CHANGE FROM GEOCENTRIC TO HELIOCENTRIC Ptolemy & Aristotle didn’t have the _____________________________________to make good _____________________________________ Ptolemy could _________________________, but the model was very complicated and he didn’t make many observations Copernicus, Kepler, Galileo, & Newton each _________________________________________________ to the development of the Heliocentric Model

FORMATION OF THE SOLAR SYSTEM According to dating of rocks, scientists believe the solar system is approximately _____________________________ ______________________________________: model for the formation of the solar system in which the sun and planets condense from a cloud (or nebula) of gas and dust. NEBULAR MODEL PROCESS Nebula began to collapse due to gravity Nebula then formed a _______________________________ Supporting evidence for the disk: Planets lie in the _____________________________________ Planets have almost circular orbits (they are ellipses though) Planets orbit in the same direction as the material in the center.

NEBULAR MODEL PROCESS, CONTINUED Center becomes hottest part with most material = ___________________ ___________________________ formed around the Sun by the accretion of matter in the disk. PLANETESIMAL = ________________ that become ___________ 4a) Planetesimals become larger as gravity attracts more material to them 4b) They then ______________________________________________ to become even larger = the Planets

Nebular Model

Think! What are 2 pieces of evidence that support the Nebular Model?

SOLAR SYSTEM BODIES SMALLER THAN MOONS ASTEROID: fragments of rock that orbit the sun ___________________________ of the “smaller” bodies Asteroid Belt = Between ___________________________________ COMET: small body of _________________________________________________ loosely packed together that follows an elliptical orbit (“dirty snowballs”) Some comets have two tails: ___________________________________: made of gases; blown by solar wind so it always is pointed away from the sun ___________________________________: made of dust; less affected by solar wind so often curved by the comet’s orbital motion

Halley’s Comet Orbits the sun every _____________________ Next time it passes the Earth is in 2061 Notice two tails

SOLAR SYSTEM BODIES SMALLER THAN MOONS METEOROID = small pieces of rock that _________________________________________________. METEOR = meteoroid that _________________________________________________(most burn up before reaching the ground). “Shooting Stars” = meteors METEORITE = meteor that ___________________________

Think! How are “smaller bodies” (asteroids, comets, and meteoroids) the same? How are they different?