3
votes
0answers
33 views

Surface UV exposure with cooler star

If the sun's surface was ~ 4000K (and earth closer to compensate), the UV component of the radiation would be less. However, UV makes ozone via photolysis of oxygen. Also, the stratosphere would ...
4
votes
2answers
722 views

Can extra-solar gamma rays reach the Earth's surface?

Can gamma rays of high enough energy entering our planet's atmosphere reach the surface (50% probability)? Or, in other words, is there a window for extremely high-energy gamma rays like for the ...