Naked Science Forum

Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: mcjhn on 16/08/2010 03:27:15

Title: If gamma rays are so penetrating, why can our atmosphere stop them?
Post by: mcjhn on 16/08/2010 03:27:15

if our atmosphere is so good at stopping gamma rays why do we need thick lead/concrete walls in nuclear reactors?

is it because 3km of gas is equivalent to a thick lead/concrete wall?

or not many gamma rays to start with compared to a nuclear reactor?

or something else?

thanks!

mark

Title: If gamma rays are so penetrating, why can our atmosphere stop them?
Post by: JP on 16/08/2010 04:42:15

Quote from: mcjhn on 16/08/2010 03:27:15

is it because 3km of gas is equivalent to a thick lead/concrete wall?

or not many gamma rays to start with compared to a nuclear reactor?

Certainly, the atmosphere has as much stopping power to gamma rays as a very thick piece of lead.  Source: NASA (http://imagine.gsfc.nasa.gov/docs/ask_astro/answers/970718.html)

(It's much thicker than 3 km, by the way--roughly 100 km thick). 

Title: If gamma rays are so penetrating, why can our atmosphere stop them?
Post by: CreativeEnergy on 16/08/2010 17:15:26

Of course, if you had a gamma-ray burst (GRB) resulting from the core collapse of an extremely massive star in close proximity to the Earth with one of its bipolar jets aimed directly at the Earth, then it would be an entirely different story. The surface of the Earth would quite literally be sterilized.

But other than that, JP is correct. [;)]