Returns the number of years a person that has lived for 'seconds' seconds is aged on 'planet'

space_age.ex

defmodule Utils.SpaceAge do
  @type planet ::
          :mercury
          | :venus
          | :earth
          | :mars
          | :jupiter
          | :saturn
          | :uranus
          | :neptune

  @doc """
  Returns the number of years a person that has lived for 'seconds' seconds is
  aged on 'planet'.
  """
  @spec age_on(planet, pos_integer) :: float
  def age_on(planet, seconds) do
    earth_years = seconds / 31557600
    case planet do
      :mercury -> earth_years / 0.2408467
      :venus -> earth_years / 0.61519726
      :earth -> earth_years
      :mars -> earth_years / 1.8808158
      :jupiter -> earth_years / 11.86215
      :saturn -> earth_years / 29.447498
      :uranus -> earth_years / 84.016846
      :neptune -> earth_years / 164.79132
    end
  end
end