The Fine Structure Constant and Habitable Planets
  We use the existence of habitable planets to impose anthropic requirements on
the fine structure constant, $\alpha$. To this effect, we present two
considerations that restrict its value to be very near the one observed. The
first, that the end product of stellar fusion is iron and not one of its
neighboring elements, restricts $\alpha^{-1}$ to be $145\pm 50$. The second,
that radiogenic heat in the Earth's interior remains adequately productive for
billions of years, restricts it to be $145\pm9$. A connection with the grand
unified theory window is discussed, effectively providing a route to probe
ultra-high energy physics with upcoming advances in planetary science.
