Instruction:

    We will be using the Exploring the Planets Software for this lesson.  This page will provide you notes and comments on what we cover in the program.  Any text that is underlined in Green is a button link in the Planets program for more information, and cannot be linked to from this website.  Links to other sites that can be reached from this website will be underlined in blue.  Key terms will be in red.

Slide Number

1. Canada's Manacovagan Crater, gives us an example of cratering on the Earth.  Hundreds of craters have been discovered on Earth.  Many are buried by sediments, others are so large they can only be seen from satellites.
2. The Manacovagan crater is 65 km across.  A short video shows how over time it has eroded down into a circular lake.
3. Barringer Crater in Arizona is probably the most famous.  This aerial view shows the floor below the surface level and the circular rim.
4. This 1 km wide crater is small compared to most craters but would need 20 million tons of TNT to be created today.
5. This slide shows a close up view of the rocks making the rim.  One of the boulders has a man standing next to it showing that it is several stories tall and as big as a building.
6. The formation of a crater step by step.  First the approaching asteroid hits while traveling at nearly 10 km/s
7. Next the energy of motion is converted into heat.  Most of the original meteor is vaporized.  A shock wave starts compressing the surface rock layers downward.
8. The compressional shock wave shatters the surrounding layers of rock.
9. Like a balloon that has been pushed in, the compressed layers of rock rebound, throwing fragmented rock, dust and dirt into the air.
10. Loose material along the sides collapses into the crater forming Breccia. In class we observed samples of volcanic and sedimentary breccia.  Breccia is a rock composed of the jagged fragments and pieces of other rock.
11. This slide shows a video of impact studies.  It can be played in slow motion to see the steps of an impact.
12. There has also been an observed impact of a comet on Jupiter in 1994.
13. The Jupiter impacts created fireballs larger than the size of the Earth.  The comets hit at 60 Km/sec.
14. Various pictures of the comet impact sites.
15. An upclose view of a young fresh crater.
16. Activity: Asteroid Impacts on the Moon.  This sldie provides data fot the size and depth of asteroid impacts.
17. Activity: Continued.  Graphing the relationship between size and depth.
18. Answer:  For every km in crater width the crater is .2km deep.
19. This relationship does not work for giant craters which often show central peaks, terraced walls, and flat floors.