We can figure out what time it is anywhere on Earth But with the moon poised to be a big player in space exploration scientists now realize they must also define what time it is there Romilly Lockyer/The Image Bank/Getty Images Plus By Tammy Awtry A quick glance at your watch or phone tells you the local time. Figuring out the time elsewhere is fairly easy — if you know its time zone. But what if you want to know the time somewhere not on Earth, such as on our moon? In fact, nobody knows what time it is on the moon. And that could pose big problems for future astronauts That’s why scientists are hard at work trying to figure out what moon time should be It’s been 50 years since the last astronaut stepped on the moon there was no need for a designated moon time astronauts could easily stick with the time used by their team leaders on Earth He works for the European Space Agency (ESA) in Noordwijk-Binnen But the moon is about to become a big player in space exploration — and longer missions. Space agencies around the world see its potential for big scientific discoveries. NASA’s Artemis program is readying to send astronauts back to the moon Permanent bases will be established where astronauts can live and study lunar science. There, they will test systems to communicate with each other and Earth, as well as learn how to make living on Mars possible.  And when we are ready to travel to Mars Scientists have realized they need an official moon time to efficiently carry out such big plans But establishing moon time is no simple matter There are lots of things to consider and agree upon time on the moon ticks off at a different rate than that on Earth So moon time will always be out of sync with the time experienced by anyone back on our planet “If we want [humans] to populate the moon and we will need some reference time for the moon — “like we have on Earth.” Defining moon time would let astronauts work together and organize their days It would be chaos if everyone followed their own time clocks and time zones are based on what’s known as Coordinated Universal Time (This reference time is equal to the old Greenwich Mean Time That means it’s five hours behind the UTC clock Moon time could synchronize with UTC — or tick independently of it Meynadier works at the Bureau of Weights and Measures (BIPM) outside Paris “I’m biased because I take care of UTC,” Meynadier admits “The U in UTC stands for universal.” And to his mind He’s referring to the fact that most life on Earth operates on a roughly 24-hour — or day-long — cycle. It’s known as a circadian cycle But a moon day lasts roughly 29.5 Earth days Our bodies are not wired to cope with roughly month-long days Relating moon time to UTC as we attempt to maintain a 24-hour day could keep our bodies on a healthier schedule Global Positioning System (GPS) receivers are all around us, including in our smartphones and in many cars. GPS tells us how to get where we want and how to get home when we’re lost. To do this, it uses satellites and receivers More than 30 GPS satellites orbit high above Earth They constantly send out signals that the receiver in your smartphone can hear Because your phone knows where each satellite is in space it can calculate how long the GPS signal took to reach you a GPS receiver calculates how far you are from four satellites The receiver in a smartphone can identify where you are within 4.9 meters But determining your location with GPS requires knowing exactly what time it is the more precisely you can know where you are which can measure time down to the nanosecond (one billionth of a second) Accurately pinpointing where you are — or want to go — in space is a big concern for scientists and astronauts a navigation system is being planned for the moon Satellites with atomic clocks will be put in orbit around the moon This will allow astronauts to know where they are as they explore the lunar surface and how to find their way back to base if they get lost Simply put: The stronger the pull of gravity Albert Einstein predicted this with his general theory of relativity Gravity on the moon is weaker than on Earth (think of astronauts bouncing effortlessly on the lunar surface) So lunar clocks will tick about 56 microseconds (0.000056 seconds) faster per day This won’t make much of a difference when astronauts plan their days it will greatly affect how well their navigation systems work accurate GPS requires knowing time down to the nanosecond And a difference of 56 microseconds is 56,000 nanoseconds So for lunar navigation systems to work correctly astronauts will need clocks that account for the moon’s gravity life on Earth has come to depend on the internet Living on the moon will require a similar system “LunaNet is like the internet if it were combined with GPS,” explains Cheryl Gramling It’s based at the Goddard Space Flight Center in Greenbelt LunaNet aims to combine the best of both GPS and the Web It can send and receive information as well as know your location So LunaNet will allow your moon selfies to be marked with the time and location at which you took them — and send them home to Earth (to make your friends jealous) It’s needed so people “can safely land on the moon then explore by planning their route from one location to another.” It will aid navigation and help astronauts figure out “how long it will take to get back to the habitat in time for dinner.” space crews and rovers will need to share information back and forth moon crews will be able to send data about their discoveries to Earth — and even video chat with their families So scientists want it tied to atomic clocks whose ticking rates will be governed by the moon’s gravity True universal time “does not exist,” Meynadier explains “There is no absolute time.” People have defined time for their planet Now it is necessary to do it for other celestial bodies all nations need to speak the same time language NASA and ESA are the agencies working to define moon time He works at ESA as a radio navigation engineer in Noordwijk-Binnen The space agencies began their discussions on devising a moon time last November at ESA’s European Space Research and Technology Center in the Netherlands NASA and ESA recognize that many nations will one day use the moon They now hope other space agencies will help in defining its time Neither NASA nor ESA is sure when a decision on the moon’s time will emerge It’s a complex problem that needs to be done right to avoid problems in the future Operating systems from different nations need to adopt the same timescale so they can work together we are left to dream about the future of space exploration When we travel through time zones on Earth our smartphone adjusts and gives us the correct time for where we are ESA engineer Hahn hopes something similar can one day tell us moon and Mars time astronaut: Someone trained to travel into space for research and exploration astrophysicist: A scientist who works in an area of astronomy that deals with understanding the physical nature of stars and other objects in space atomic clock: A timekeeping device that relies on the frequency of microwave emissions from excited atoms for the cesium atom that frequency is 9,192,631,770 hertz (or cycles/oscillations per second) computers and GPS-satellite receivers rely on the high accuracy of atomic clocks to regularly reset their time (known as synchronization) The scientists who study them are known as biologists celestial: (in astronomy) Of or relating to the sky chaos: A situation that is confused and has no order (in physics) A situation where the behaviors of a system appear random and unpredictable Chaos arises because the system is exquisitely sensitive to even small changes in the conditions that define it data: Facts and/or statistics collected together for analysis but not necessarily organized in a way that gives them meaning For digital information (the type stored by computers) those data typically are numbers stored in a binary code engineer: A person who uses science and math to solve problems material or process that will solve some problem or unmet need global positioning system: Best known by its acronym GPS this system uses a device to calculate the position of individuals or things (in terms of latitude longitude and elevation — or altitude) from any place on the ground or in the air The device does this by comparing how long it takes signals from different satellites to reach it gravity: The force that attracts anything with mass habitat: The area or natural environment in which an animal or plant normally lives A habitat can be home to thousands of different species internet: An electronic communications network It allows computers anywhere in the world to link into other networks to find information download files and share data (including pictures) literally: An adjective indicating that the phrase it modifies is precisely true to say: "It's so cold that I'm literally dying," means that this person actually expects to soon be dead But its diameter is only about half as big as Earth’s NASA: Short for the National Aeronautics and Space Administration agency has become a leader in space research and in stimulating public interest in space exploration It was through NASA that the United States sent people into orbit and ultimately to the moon It also has sent research craft to study planets and other celestial objects in our solar system orbit: The curved path of a celestial object or spacecraft around a galaxy One complete circuit around a celestial body planet: A large celestial object that orbits a star but unlike a star does not generate any visible light satellite: A moon orbiting a planet or a vehicle or other manufactured object that orbits some celestial body in space smartphone: A cell (or mobile) phone that can perform a host of functions including search for information on the internet system: A network of parts that together work to achieve some function vessels and heart are primary components of the human body's circulatory system roadway signals and overpasses are among the potential components of a nation's railway system System can even be applied to the processes or ideas that are part of some method or ordered set of procedures for getting a task done technology: The application of scientific knowledge for practical purposes processes and systems that result from those efforts or UTC: It's the successor to Greenwich Mean Time (the former standard for time) Other time zones are measured by how many hours their clocks (or time) vary from UTC-0 usually due to some twisting or curving in a normally flat surface or plane A piece of wet lumber may warp as it dries unevenly Web: (in computing) An abbreviation of World Wide Web Website: European Space Agency. Telling time on the moon. February 27 Report: J. Esper. LunaNet Interoperability Specification Document Version 4 Report: J. Schier. LunaNet Overview Unique Science from the Moon in the Artemis Era Workshop Website: LunaNet: Empowering Artemis with communications and navigation interoperability. October 6 Website: NASA. What is GPS award-winning online publication dedicated to providing age-appropriate science news to learners a nonprofit 501(c)(3) membership organization dedicated to public engagement in scientific research and education