Impacts and Craters
Possible Issues and Questions

Students may become frightened or overly concerned about the possibility of a future impact on the Earth.

Students may encounter information disputing or attributing asteroid and comet impacts to mass extinctions on Earth. There have been several mass extinctions in Earth's history; while there is some geological evidence for impacts as the same time as many of these mass extinctions, there may have been additional factors; the underlying cause for most mass extinctions is still in dispute.

Students may be confused over the enormous size of some impact basins on the Moon, Mars, and other planets, compared to the relatively small sizes of craters on Earth. The effects of erosion and plate tectonics has obliterated the traces of most impacts that have occured in Earth's history.