Mercury’s Craters How They Are And What They AreFrom the Beginning…On Mercury, How Is It Different?How Do Craters Form?What Kinds Exist?Formation of Simple CratersFormation of Complex CratersWhat These Craters Tell UsMercurian CratersSize of Craters on MercuryThe Largest Craters on MercuryWhat These Craters Mean for ScientistsMercury’s CratersMercury’s CratersHow They Are And What They How They Are And What They AreAreLindsay JohannessenPTYS 495oHow do craters form?oWhat kinds of craters are there?oWhat are the circumstances of how these craters form?oWhat does this tell us about our history?On Mercury, How Is It On Mercury, How Is It Different?Different?oMost common types?oDispersion throughout region and numbers!oThe biggies… Why are they so interesting?oAmazing effects on Mercury!How Do Craters Form?How Do Craters Form?oCraters occur on any and every solid bodied mass in the Universe. oCraters’ shapes and sizes depend on three things:- Mass density of projectile object and of impacted surface.- Diameter of projectile object.- Velocity of projectile object.What Kinds Exist?What Kinds Exist?Simple Craters:Single ridged with ejectoblanket No caving rimsRetains excavation stage shapeComplex CratersHave central peakOuter rims collapse to enlarge diameterLarger in generalDouble and Multi-ringed CratersLarger than central peak complexHave second (sometimes multi) internal ringcaused from reverberation of impactFormation of Simple CratersFormation of Simple CratersImpact occursSeismic waves travel throughimpactor and impactedCrush, melt and vaporize mostof the impactorExcavation crater is left as main craterFormation of Complex CratersFormation of Complex CratersSame initial process assimple cratersFrom bigger impacts comebigger resultsCentral peak and secondaryRings form from reverberationof initial impactWhat These Craters Tell UsWhat These Craters Tell UsGiven consistent information:Date ranges for bombardment periodsPossible surface structureQuantifiable forces involved in impactsMercurian CratersMercurian CratersGenerally larger and more violent than what we usually see in our Solar SystemMercury’s Gravitational Pull= 370 cm/sec²Average impact speed for:Asteroid = 34km/secComet = 87 km/secSize of Craters on MercurySize of Craters on MercurySimple craters on Mercury:Range up to approx. 10 km in Diameter(19 km on the Moon and 3 km on Earth)Complex Craters:Range from 10km up to 200km with a central peakRange from about 200km to 750km with Double RingRange from 750km to 1500 and up with multiple rings.The Largest Craters on MercuryThe Largest Craters on MercuryThe Caloris Basin is known to be the largest crater basin in the Solar System.Effects of the larger impacts are as great as planetary change.Antipodal changes in the surfaceof the planet are a major sideeffect of this large impact.What These Craters Mean for What These Craters Mean for ScientistsScientistsBy studying all effects of Mercury’s impact history, we can discern eras of impacting, possible sources of impacting, (i.e. asteroid belts, comets, etc…), and ascertain the historical records of Mercury through observation, data collection and