CRATERS


What is a crater?

Definition: A crater is a bowl-shaped depression, or hollowed-out area, produced by the impact of a meteorite, volcanic activity, or an explosion.
external image lunar_crater.jpg

What are the major parts of a crater?

  • Floor The bottom of a crater, either bowl-shaped or flat, usually below the level of the surrounding ground.
  • Central peaks Peaks formed in the central area of the floor of a large crater. For larger craters (typically a few tens of kilometers in diameter) the excavated crater becomes so great that it collapses on itself. Collapse of the material back into the crater pushes up the mound that forms the central peak. At the same time, the rock beneath the crater rebounds, or bounces back up to add to the peak.
  • Walls The interior sides of a crater, usually steep. They may have giant stair-like terraces that are created by slumping of the walls due to gravity.
  • Rim The edge of the crater. It is elevated above the surrounding terrain because it is composed of material pushed up at the edge during excavation.
  • Ejecta Rock material thrown out of the crater area during an impact event. It is distributed outward from the crater's rim onto the planet's surface as debris. It can be loose materials or a blanket of debris surrounding the crater, thinning at the outermost regions.
  • Rays Bright streaks extending away from the crater sometimes for great distances, composed of ejecta material.


external image aristarchus1.jpg
Aristarchus, named after the Greek astronomer Aristarchus of Samos, is a prominent lunar impact crater that lies in the northwest part of the Moon's near side.

external image Meteorcrater.jpg
Meteor Crater is a meteoriteimpact crater approximately 37 miles (60 km) east of Flagstaff and 18 miles (29 km) west of Winslow in the northern Arizona desert of the United States

How many different craters are there?

  • Impact Craters
  • Volcanic Craters
  • Explosion crater

Impact craters:

  • What is an Impact crater?
https://www.nasa.gov/pdf/180572main_ETM.Impact.Craters.pdf
  • The process of an Impact Crater:
http://www.impact-structures.com/understanding-the-impact-cratering-process-a-simple-approach/

Volcanic craters:

  • What is a volcanic crater?
“It is a bowl-shaped geological formation at the top of a volcano”
http://www.universetoday.com/31143/volcano-crater/
  • How is a volcanic crater formed?
http://geology.com/articles/caldera/

Explosion crater:

  • What is an Explosion crater?
“An explosion crater is a type of crater formed when material is ejected from the surface of the ground by an explosive event at or immediately above or below the surface”
https://en.wikipedia.org/wiki/Explosion_crater

How to measure a crater:

You can click on the link below for a video on how to measure a crater;
http://iopscience.iop.org/article/10.1088/0031-9120/48/4/520/meta

How to draw different types of craters/features of a crater:

http://i38.photobucket.com/albums/e140/chelsaenevarez/How%20to%20draw%20a%20crater_zpsylassoum.jpg

What is a;


1. Flat floored crater;
http://link.springer.com/referenceworkentry/10.1007/978-1-4614-9213-9_440-1#page-1

2. Wrinkled ridge crater;
https://en.wikipedia.org/wiki/Wrinkle_ridge

3. Rille crater;
https://www.britannica.com/science/rille

4. Central peak;
http://physics.stackexchange.com/questions/26091/how-does-the-central-peak-in-moon-craters-form

5. Over lapping crater;
https://www.uwgb.edu/dutchs/planets/crathist.htm

6. Round floored crater;
http://onlinelibrary.wiley.com/doi/10.1029/JB091iB13p00E75/abstract