On the Formation Age of the First Planetary System
  Recently, it has been observed the extreme metal-poor stars in the Galactic
halo, which must be formed just after Pop III objects. On the other hand, the
first gas clouds of mass $\sim 10^6 M_{\odot}$ are supposed to be formed at $ z
\sim $ 10, 20, and 30 for the $1\sigma$, $2\sigma $ and $3\sigma$, where the
density perturbations are assumed of the standard $\Lambda$CDM cosmology. If we
could apply this gaussian distribution to the extreme small probability, the
gas clouds would be formed at $ z \sim $40, 60, and 80 for the $4\sigma$,
$6\sigma$, and $8\sigma$. The first gas clouds within our galaxy must be formed
around $z\sim 40$. Even if the gas cloud is metal poor, there is a lot of
possibility to form the planets around such stars. The first planetary systems
could be formed within $\sim 6\times 10^7$ years after the Big Bang in the
universe. Even in our galaxies, it could be formed within $\sim 1.7\times 10^8$
years. It is interesting to wait the observations of planets around metal-poor
stars. For the panspermia theory, the origin of life could be expected in such
systems.
