What time is it on the moon?

James Olthoff, a delegate to the International Bureau of Weights and Measures, talks to NPR's Joel Rose about why it's important to accurately measure time on the moon. NPR Science LISTEN & FOLLOW NPR App Apple Podcasts Spotify Amazon Music iHeart Radio RSS link Science What time is it on the moon? October 18, 20265:00 PM ET Heard on All Things Considered By  Henry Larson ,  Joel Rose What time is it on the moon? Listen · Transcript Toggle more options Download Embed Embed <iframe src="https://www. npr. org/player/embed/nx-s1-6003578/nx-s1-9968725" width="100%" height="290" frameborder="0" scrolling="no" title="NPR embedded audio player"> Transcript James Olthoff, a delegate to the International Bureau of Weights and Measures, talks to NPR's Joel Rose about why it's important to accurately measure time on the moon. Transcript JOEL ROSE, HOST: What time is it on the moon? The answer is very much up in the air. One lunar day is almost a month on Earth, and time ticks . So the watch you bring from Earth wouldn't be quite accurate. This week, representatives from 69 countries grappled with this very question at an international conference in Versailles, France, including James Olthoff. He is a delegate to the International Bureau of Weights and Measures, and he joins us now from the conference. I'm happy to be here. ROSE: Why does the time on the moon matter? OLTHOFF: As we do more and more exploration on the moon and establish more and more presence there, the goal would be to have the ability to do precision navigation on the moon to know exactly where we are. And since there are so many players, there needs to be some coordination in terms of how they're all telling time. ROSE: What is the worst-case scenario if they can't work together? OLTHOFF: Well, it might be possible that you wouldn't be able to know exactly where you were on the moon, that you wouldn't be able to accurately map the moon. It's just a question of being able to actually function efficiently there. ROSE: You attended a session at this week's conference that was all about this issue. What are the options that are being considered? OLTHOFF: Fundamentally, there is one option that would be specific, more or less, to the moon, and that's one way to proceed. And that is actually the simplest way, although far from simple. One might like to establish a system for telling time everywhere in the solar system, and so that would be a little more complicated to implement but in the long term would allow you to apply the same system if you were on Mars.