Statement: The impact of extraterrestrial bodies can cause major changes to earth systems.

To effectively make a significant change to the earth's atmosphere the meteor can be much smaller then the one known for making the K-T crater. Major changes can occur from an impact creating a creator twenty kilometers or more in diameter, which would only require a meteor .5km or more in diameter. Impacts of this size have the possibility of altering the terrestrial climate and biosphere. These impacts can affect the light levels of the planet and cause temperature disruptions equal to that of a nuclear winter. The affects on the atmosphere from a meteor could produce higher sulfur levels in the atmosphere and cause a temperature decrease of up to 7 degrees.

One example of an instance which affected both the biosphere and terrestrial climate is K-T

(Cretaceous - Tertiary). This...