Wondering how to tell time in the moon? In 1970, Helbros Watches asked Kenneth L Franklin, chief astronomer at New York’s Hayden Planetarium, to design a watch for moon walkers that measures time in  “lunations,” the period it takes the moon to rotate and revolve around the Earth; each lunation is exactly 29.530589 Earth days. Franklin developed a system called “lunar mean solar time,” or Lunar Time (LT).   He envisioned local lunar time zones similar to the standard time zones of Earth, but based on meridians that are 12-degrees wide (analogous to the 15-degree intervals on Earth).   A lunar hour was defined as a “lunour”