An exponential model of continuous galactic synthesis is used to analyze new data on the abundance in meteorites, the Earth, and the moon of several transactinium nuclei, particularly plutonium-244. It is shown that nucleosynthesis in our galaxy occurred over a period of six billion years up to the formation of the solar system. The possibility of a change in nuclear stability in the past as the result of change in the universal constants is also discussed. It is shown that this possibility is greatly limited but that a direct check of the constancy of the constants could be obtained by comparison of the radii of pleochroic rings in old micas with contemporary $\alpha$-particle ranges.