This photograph shows the Royal Greenwich Observatory in Greenwich Park in south-east London. Earth time zones were developed from the Prime Meridian, here at Greenwich. Now, scientists are developing a time zone for the Earth;s Moon.
(Image Source: Wikipedia.org, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=334711)
By Glenn A. Walsh
Reporting for SpaceWatchtower
Time on the Moon is about to become “coordinated”. Both the American Government and the European Union are studying how to establish Coordinated Lunar Time. And, Coordinated Lunar Time would also lead to a separate Global Positioning System (GPS) specifically for the Moon.
Coordinated Lunar Time will be determined by the weighted averaging of atomic clocks on the Moon's surface. This is similar to how standard time is determined on Earth. This project includes the consideration of where on the Moon to place the atomic clocks.
Such a new time standard was first proposed by the European Space Agency (ESA) in early 2023. In April of 2024, the White House asked NASA [through the agency's Space Communication and Navigation (ScaN) Program] to work with U.S. and international scientific agencies for the purpose of establishing Coordinated Lunar Time.
The title of the new lunar time zone comes from Coordinated Universal Time, the Earth time based at the Prime Meridian, established by Great Britain at the beginning of their naval dominance. The Prime Meridian was centered at Britain's Royal Greenwich Observatory, located in Greenwich Park in south-east London.
Today, Coordinated Universal Time (previously known as Greenwich Mean Time and Greenwich Civil Time) is the standard time used by scientists and navigators. All other standard time zones throughout the world are derived from Coordinated Universal Time. Each of the other 23 hourly time zones are a certain number of hours ahead or behind the time zone at the Prime Meridian (occasionally, a half-hour time zone exists, as for the Canadian province of Newfoundland).
Space missions to the Moon now use either Coordinated Universal Time or the time zone of origin of the space mission. This time could be Houston time (Central Time Zone at NASA's Johnson Space Center), Los Angeles time (Pacific Time Zone for Pasadena's Jet Propulsion Laboratory of the California Institute of Technology), Moscow time (for Russian missions), China Standard Time (for Chinese missions), or Indian time (for missions from India).
As more nations and private companies send missions to the Moon, there needs to be a common time zone, that all space missions use, to avoid confusion.
Further, time passes on the Moon, and in lunar orbit, at different rates. And, these times also differ from how time passes on the Earth or in Earth orbit.
This is due to the fact that clocks tick more slowly when in Earth orbit, than clocks on the ground. This is also true for the Moon and lunar orbit.
Also, clocks on the Moon tick fractionally faster than clocks on Earth, because the Moon has a much less gravitational attraction than gravity on the Earth. Gravity on the Moon is about 1/6 the attraction of gravity on Earth.
Plus, scientists have to consider that the Moon orbits the Earth. So, as the Earth's gravity is strong enough to keep the Moon in Earth orbit, the Earth's gravity can also have an affect on lunar time.
The lunar time standard being proposed would solve these types of time-keeping issues. According to Arati Prabkahar, who was the Director of the White House Office of Science and Technology Policy and Science Advisor to the President (during much of the Administration of U.S. President Joe Biden), lunar time would currently "appear to lose on average 58.7 microseconds per Earth-day and come with other periodic variations that would further drift Moon time from Earth time"
For perspective, consider that a hummingbird's wings flap at a rate of about 50 times per second. Each flap has a duration of about 0.02 second or 20/000 microseconds.
This is all due to the effects of relativity. Albert Einstein's General Theory of Relativity states that gravity affects time, or space-time as he referred to it. Dr. Einstein's research showed that time does not flow uniformly everywhere. Hence, scientists must grapple with all of the variations in time at different locations, to ensure that clocks and GPS work properly in any locality.
Once developed, this new time standard is meant to be used by all nations and companies sending missions to the Moon. Initially, it will be developed and instituted through a collaboration of members of the Artemis Accords. The Artemis Accords (named for the Artemis mission to send U.S. astronauts, including the first woman and the first astronaut of-color, back to the Moon) are a series of non-binding, multilateral arrangements between the United States and other governments on Earth, which elaborates on the norms expected by space-faring nations.
There are four key features of this new time standard, initially:
Traceability back to Coordinated Universal Time.
Accuracy sufficient for navigation and science.
Resilience to disruptions.
Scalability to potential environments beyond the Earth – Moon system.
In August of 2024, the U.S. National Institute of Standards and Technology (NIST) released a draft of the proposed standard. The draft focuses on the framework and mathematical model, which takes into account the gravitational differences on the Moon.
This draft was published in The Astronomical Journal, a leading scientific publication.
A unified time standard for the Moon, and possibly including other celestial bodies, is expected by 2026, as requested by the Biden Administration.
Internet Links to Additional Information ---
The Moon of Earth: Link >>> https://en.wikipedia.org/wiki/Moon
Timekeeping on the Moon: Link >>> https://en.wikipedia.org/wiki/Timekeeping_on_the_Moon
NASA News Release: "NASA to Develop Lunar Time Standard for Exploration Initiatives":
Link >>> https://www.nasa.gov/general/nasa-to-develop-lunar-time-standard-for-exploration-initiatives/
NIST News Release: "What Time Is It on the Moon?":
Link >>> https://www.nist.gov/news-events/news/2024/08/what-time-it-moon
Source: Glenn A. Walsh Reporting for SpaceWatchtower, a project of Friends of the Zeiss
"Coordinated Lunar Time Zone for the Moon"
Monday, 2025 January 27.
Artificial Intelligence not used in the writing or production of this article.
© Copyright 2025 Glenn A. Walsh, All Rights Reserved
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Glenn A. Walsh, Informal Science Educator & Communicator (For more than 50 years! - Since Monday Morning, 1972 June 12):
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Electronic Mail: < gawalsh@planetarium.cc >
Project Director, Friends of the Zeiss: Link >>> http://buhlplanetarium.tripod.com/fotz/
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Formerly Astronomical Observatory Coordinator & Planetarium Lecturer, original Buhl Planetarium & Institute of Popular Science (a.k.a. Buhl Science Center), America's fifth major planetarium and Pittsburgh's science & technology museum from 1939 to 1991.
Formerly Trustee, Andrew Carnegie Free Library and Music Hall, Pittsburgh suburb of Carnegie, Pennsylvania, the fourth of only five libraries where both construction and endowment funded by famous industrialist & philanthropist Andrew Carnegie.
Author of History Web Sites on the Internet --
* Buhl Planetarium, Pittsburgh: Link >>> http://www.planetarium.cc Buhl Observatory: Link >>> http://spacewatchtower.blogspot.com/2016/11/75th-anniversary-americas-5th-public.html
* Adler Planetarium, Chicago: Link >>> http://adlerplanetarium.tripod.com
* Astronomer, Educator, Optician John A. Brashear: Link >>> http://johnbrashear.tripod.com
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