Who decides what time it is on the Moon
Eight organisations with a stated role in the lunar time standard: what each one decides, the document or paper that says so, and what none of them has done yet.
Key facts
- The 28th General Conference on Weights and Measures meets from 13 to 15 October 2026 in Versailles, with lunar time on its provisional agenda. [1]Official
- A White House memorandum of 2 April 2024 gives NASA until 31 December 2026 to deliver a finalized lunar time implementation strategy. [2]Official
- The International Astronomical Union defined Lunar Coordinate Time in 2024 and asked other bodies to agree its relation to UTC. [3]Official
- Agencies compared positions on cislunar timing at the joint ICG-IOAG workshop in Vienna on 10 to 13 February 2026. [4]Official
- Agencies meeting at ESTEC in November 2022 agreed that a common lunar reference time was important and urgent. [5]Official
How a record gets on this page
An organisation gets a record here when the registry holds checked sources about it: three or more facts, each with its own document behind it. Ten bodies were considered. Two of them, the Japanese space agency and the International Association of Geodesy, have no source in our registry that says anything about lunar time, so they have no record and no page. A record without a source would look exactly like the eight that have one, and that is the failure mode this rule exists to prevent.
Nobody on this page runs a lunar clock. Every clock value on this site is a model value, computed from published rate figures; no lunar time scale has been realized [3]Official. Where each body stands today, with its next dated milestone, is onthe standards tracker; the documents themselves are in the primary documents hub; and the missions and programmes these bodies run, with the window each source gives, are inwhere lunar time is needed.
Who holds which decision
The bodies below are not competing to answer one question. Each holds a different piece: a definition, a vote, a rate figure, a deadline, a room where positions meet. The table names the piece and the source it comes from.
| Organisation | Type | The piece it holds | Source |
|---|---|---|---|
| NASA | Space agency | What the United States will propose as the practical lunar time standard, and on what schedule. | [2]Official |
| BIPM | Standards body | Which text on lunar time is put to the member states of the metre convention, and in what wording. | [6]Official |
| IAU | Scientific union | The definition of the lunar coordinate time other bodies build on, and the epoch it starts from. | [7]Official |
| NIST | National institute | The published model rate between a lunar surface clock and an Earth surface clock, and its stated uncertainty. | [8]Official |
| ESA | Space agency | Which time reference the Moonlight communication and navigation service distributes to its users. | [5]Official |
| PMO | National institute | How TCL is computed in practice, and with what stated accuracy, for anyone who needs the transformation today. | [9] |
| USNO | National institute | Nothing about the lunar scale itself, in any document we hold: it appears as one end of the traceability chain. | [2]Official |
| ICG | Coordination forum | Where navigation and space agencies state their positions on lunar reference and time systems before any vote. | [4]Official |
The eight records
Each record carries the same structure: a table of what the organisation is, key facts with sources, what it decides, and the pages on this site it connects to. The plain-language background common to all of them is inwhat Coordinated Lunar Time is.
National Aeronautics and Space Administration
United States civil space agency; it says it will develop a lunar time standard for its missions and for LunaNet.
Bureau International des Poids et Mesures
Intergovernmental metrology organisation that prepares the draft resolutions put to the General Conference on Weights and Measures.
International Astronomical Union
Astronomical union whose 2024 General Assembly adopted the resolutions on the Lunar Celestial Reference System and Lunar Coordinate Time.
National Institute of Standards and Technology
United States metrology institute; its researchers published the relativistic framework for estimating clock rates on the Moon.
European Space Agency
European space agency; it runs the Moonlight programme and set out the case for a common lunar reference time.
Purple Mountain Observatory, Chinese Academy of Sciences
Chinese observatory whose group published the LTE440 lunar time ephemeris built on the IAU definition of Lunar Coordinate Time.
United States Naval Observatory
United States timekeeping observatory; it maintains UTC(USNO), one of the two national realizations of UTC named in the 2024 lunar time policy.
International Committee on Global Navigation Satellite Systems
United Nations forum for navigation providers; with the IOAG it runs the multilateral workshops on cislunar positioning, navigation and timing.
Sources
- 28th meeting of the CGPM (2026)
- Policy on Celestial Time Standardization
- Resolution on the establishment of a coordinated lunar time standard by international agreement
- 2nd Joint ICG-IOAG Multilateral Cislunar PNT Workshop
- Telling time on the Moon
- Convocation of the 28th meeting of the CGPM (O/Ref AK-CFA-2026-1001)
- Resolution to establish a standard Lunar Celestial Reference System (LCRS) and Lunar Coordinate Time (TCL)
- What Time Is It on the Moon?
- Lunar Time Ephemeris LTE440: definitions, algorithm and performance
- Policy on Standardization of Lunar Reference Systems in Support of the National Cislunar Science & Technology Strategy
- NASA to Develop Lunar Time Standard for Exploration Initiatives
- A Relativistic Framework to Estimate Clock Rates on the Moon
- Moonlight
- U.S. Naval Observatory
- International Astronomical Union
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