100%(1)1 out of 1 people found this document helpful
This preview shows page 15 - 17 out of 20 pages.
Comets spend a very small percentage of one period in the inner solar system (kepler’s second law) Short Period Comets-may come from the oort cloud and have been deflected into closer oribits. Jets of sublimated gas can deflect comets in their orbitsDemise of CometsTwo comets for example, met their demise, by 1. Colliding with Jupiter, and 2. by getting to close to the sun and fragmenting.oAsteroidsRock and/or metal, mostly between mars and Jupiter. PropertiesSmall compared to planets or large satelities. Largest one, Ceres, is only 1000 km across. Mostly not sphereical (except for Ceres) Shaped more like potatoesGravity not strong enough to compress rocky material. Some are collections of “gravel”.Orbital Properties of AsteroidsAsteroids orbits are more elliptical and inclined than planetary orbits.Most are in the asteroid belt. Some share jupiters orbit. – two pass infront and behindit- the LaGrange points.Trojan asteroids cross earth’s orbit The Asteroid BeltOrbit resonances with Jupiter created gaps as in Saturn’s rings, known as Kirkwood Gaps. Resonances explain why no planet formed in the asteroid belt. Jupiter disrupted formation and scattered most planetesimals in the region. Measuring AsteroidsDiameter-from reflectivity and distanceMass-effect on a passing spacecraft or a moonDensity-mass / by volume15
Shapes- measure the asteroid’s changes in the brightness as it rotates. We can bounce radar signals off of near-earth asteroids. Asteroid Compoistion- 3 major groupsC-Type-Carbon rich, very darkoOuter regions of asteroid beltS-Type-Rocky, brighteroInner regions of asteroid beltM-Type-Metallic oRocks Falling from the SkyMeteorShooting star. Most particles are the size of a pea.MeteroritesSurvived fall to earthCaused brighter meteor a fireball Higher metal content than terrestrial rocks Contains indium and isotopes not found in terrestrial rocks.Types of Meteorites-Primitive-stony or carbon richProcessed-metallic or rocky. Origins of MeteoritesPrimitive- oformed directly from solar nebulaostony formed inside frost lineocarbon rich formed outside the first line, where carbon compounds condense.Processedocame large objects in the inner solar system. oMetallic ones are fragments of cores of asteroids shattered in collisionsoRocky ones were chipped off surfaces of asteroids, mars, and the moon impacts. Meteor ShowersWhen earth passes through comet debrisYou can see as many as one meteor per minuteShower dates correspond to when earth passes a given comet’s orbitMeteors appear to shoot from the point directly ahead in the direction that earth is moving/ named for the constellation from which the meteors appear to emanate.