I just watched Cosmos episode 5. The age of the earth was estimated by the ratio of uranium to lead in the Arizona meteorite. The premise seemed to be that the “clock” started when the rocks of our solar system were formed, became solid.

My thought: uranium and lead were created in a supernova. The uranium decay began at that time. Would not the ratio of uranium to lead found in a meteorite indicate the original ratio of uranium to lead, adjusted for the decay of uranium from the time of its (and that of the lead’s) creation? If so, this the age of the supernova not the age of the earth.

Am I missing something?

With respect,

Mike C