LTC: A Clock for the Moon

As NASA and international partners prepare for the Artemis missions and permanent lunar bases, a new problem has emerged: What time is it on the Moon? The answer is more complex than simply picking a timezone.

The 56-Microsecond Gain

Because the Moon has less mass than Earth, its gravitational field is weaker. According to General Relativity, time on the Moon ticks slightly faster than time on Earth—by about **56 microseconds** every 24 hours. While this sounds small, it is enough to cause critical failures in high-precision navigation and docking systems.

Coordinated Lunar Time (LTC)

The White House and international space agencies have directed the establishment of **Coordinated Lunar Time (LTC)**. Unlike Earth’s UTC, which is tied to leap seconds and Earth's spin, LTC will likely be a purely mathematical time scale that stays synchronized with the "proper time" as experienced on the lunar surface.

The Lunar Month vs. The Lunar Day

A "day" on the moon (the time between one sunrise and the next) lasts about 29.5 Earth days. This means a lunar base will experience two weeks of continuous sunlight followed by two weeks of freezing darkness. LTC will help manage the logistics of power and life support during these extreme cycles.

Conclusion

Establishing LTC is the first step in creating a "Solar System Internet." It establishes a standard epoch for another world. On the Epoch Clock, we are grounded on Earth, but our sister clock on the Moon is about to start its own journey.