From perpendicular angel knowledgebase
Asteroids, Meteors, and Comets
- Asteroid Fast Facts
- Asteroid impact avoidance on Wikipedia
- Bolide: an extremely bright meteor, especially one that explodes in the atmosphere
- How big does a meteor have to be to make it to the ground? Hint: Anywhere from dust on up
- How fast is a comet search results on Google
- Incoming! Meteor or Comet Fragment Explodes Above Southwestern US, Prompting US Army 'Missiles' Cover-up
- Meteor Smoke Makes Strange Clouds
- We Probably Wouldn't Even See A Doomsday Asteroid Until It Was Too Late
- The Willamette Meteorite
- How far can we see if unobstructed? Hint: usually 12 miles.
- The Atmosphere of the Earth on Wikipedia
Caves and Caving
- The Chesapeake Bay impact crater and the related boundary image
- Impact Craters Google Image Search
- Understanding the Impact Cratering Process: a Simple Approach
- Breccia: a rock composed of broken fragments of minerals or rock cemented together by a fine-grained matrix that can be similar to or different from the composition of the fragments. May be formed by an impact.
- Ringing Rocks of Montgomery County, Pennsylvania (PDF)
- Granite: a common type of felsic intrusive igneous rock that is granular and phaneritic in texture. Used for countertops, among other things. Popular in Minecraft.