I was looking at some NASA photos of Earth that were taken from orbit.
I came across these two pictures that were taken of the moon with the Earth's limb in the picture.
It occurred to me that the picture that was taken about three years later seems to have a narrower blue atmosphere area around our planet.

Naturally, I claim that it is due to the thinning of the atmosphere because of the excessive radioactive elements in the atmosphere.
I concede that there are several other possible explanations, but without further study, my theory seems logical.

Moon Set over Earth 07/14/1995

Moon Framed 11/06/1998

It seems to me that in the earlier picture the atmosphere is as thick as the moon is wide, but in the later picture the atmosphere is only about half of the moons width.
The question is: Why such a great difference in the two perspectives?