The Solar System currently lies within a low-density, irregularly shaped cavity of hot plasma called the “Local Bubble”, which extends to about 200 parsecs. Theory shows that this Local Bubble was most likely made by the powerful blast waves of supernovae, the deaths of the most massive stars. Terrestrial and lunar evidence of radioactive elements, that could have only come from supernovae, also give proof that at least two supernova explosions have occurred near-Earth within the past 10 million years, possibly affecting the climate and the development of life. We have used the kinematics of living massive stars to trace them back in time to plot where they would have been in past epochs. We have also derived an expression to estimate the number of these supernovae by using the number of massive stars near us currently, the distribution of stellar mass, and the birth and death rates Our results have expanded the previous estimates, which had focused on specific nearby stellar clusters rather than all massive stars, and increased the estimated number of supernovae within 200 parsecs of Earth to be about 26. This has an impact on the predicted flux of radioactive elements and neutrinos, which are to be investigated more in future work.
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