Mercury’s Craters How They Are And What They Are Lindsay Johannessen PTYS 495.
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Mercury’s Mercury’s Craters Craters How They Are And What How They Are And What They Are They Are Lindsay Johannessen PTYS 495
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Transcript of Mercury’s Craters How They Are And What They Are Lindsay Johannessen PTYS 495.
Mercury’s CratersMercury’s Craters
How They Are And What How They Are And What They AreThey Are
Lindsay JohannessenPTYS 495
o How do craters form?
o What kinds of craters are there?
o What are the circumstances of how these craters form?
o What does this tell us about our history?
On Mercury, How Is It On Mercury, How Is It Different?Different?
o Most common types?
o Dispersion throughout region and numbers!
o The biggies… Why are they so interesting?
o Amazing effects on Mercury!
How Do Craters Form?How Do Craters Form?
o Craters occur on any and every solid bodied mass in the Universe.
o Craters’ 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 shape
Complex CratersHave central peakOuter rims collapse to enlarge diameterLarger in general
Double and Multi-ringed CratersLarger than central peak complexHave second (sometimes multi) internal ringcaused from reverberation of impact
Formation of Simple CratersFormation of Simple Craters
Impact occurs
Seismic waves travel throughimpactor and impacted
Crush, melt and vaporize mostof the impactor
Excavation crater is left as main crater
Formation of Complex CratersFormation of Complex Craters
Same initial process assimple craters
From bigger impacts comebigger results
Central peak and secondaryRings form from reverberationof initial impact
What These Craters Tell UsWhat These Craters Tell Us
Given consistent information:Date ranges for bombardment periods
Possible surface structureQuantifiable forces involved in impacts
Mercurian CratersMercurian Craters
Generally larger and more violent than what we usually see in our Solar System
Mercury’s Gravitational Pull= 370 cm/sec²
Average impact speed for:
Asteroid = 34km/sec
Comet = 87 km/sec
Size of Craters on MercurySize of Craters on Mercury
Simple 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 The Largest Craters on MercuryMercury
The 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 ScientistsScientists
By 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 analysis.
