Origin of Solar System Origin of Solar System

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Conservation of MomentumMomentum = mass x velocityOther examples of conservationof angular momentumReview Newton’s Laws of Motion (Lecture 9).Newton’s 1st Law implies momentum is conserved (i.e. isunchanging) if there are no forces acting on an object.Newton’s 2nd & 3rd Laws imply that if a force is applied theoverall momentum is also conserved (i.e. unchanged) sincethere is always an opposite force of equal strength.Conservation of Angular MomentumAngular momentum ! mass x rotation rate x radius 2An object of constant mass will spin faster as it contractsIce skater video….Origin of the Solar System• All cold interstellar gas we seetoday has some small dust grains.We think the pre-solar nebulawould have started with these also.• Growth of these grains to largersizes and eventually to formPlanetesimals• Gravity collects planetesimals toform Protoplanets• Formation of Jovians: Largeprotoplanets sweep up gas• Formation of Terrestrials: Smallerprotoplanets, in a warmerenvironment, not able to retainlarge amounts of Hydrogen gas
Origin of the Solar System• Planets form in disk ofgas and dust near centerof nebula.We can see other solar systems forming• See star formation section later in course- Orbits are all in same direction andplane. They are approximately circular.- Change in composition of planets isdue to changes in local temperature indisk: planets are forming viacondensation and accretion and disk iswarmer near the Sun, e.g. no solidwater ice inside about 4 AU.Origin of the Solar System• Asteroids– Remaining rocky planetesimals inthe inner solar system– Failed to become protoplanets dueto gravity of Jupiter• Comets– Remaining icy planetesimals inouter solar system -> Kuiper belt– Gravitational interactions withJovians flung planetesimals• Into inner solar system (deliveringsome water to Terrestrial planets)• To outer solar system – Oort cloudRecall: The Importance of Light• We can not hope to visit objects outside the solarsystem in our lifetime.• The easiest way we can learn about distant objectsis by studying the light they emit.• Using information in their light, we can measurecompositions, temperatures, distances, masses andages of astronomical objects.• As light travels at a finite speed, by lookingfurther and further away we look back further andfurther into the past.
Page 1: Key Concepts: Lecture 18: Solar Sys
Page 5 and 6: Light Also Behaves Like A Particle!
Page 7 and 8: Kirchhoff’s Laws• Gustav Kircho

Origin of Solar System Origin of Solar System

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