In most of the U.S., clocks jumped forward by sixty minutes in the early morning hours on Sunday. The spring start of daylight saving time (what Europeans call “summer time”) is less pleasant than the time shift in autumn, when Americans gain an extra hour of sleep for the night. But while the change is unpleasant and disorienting, the extra hour of evening daylight during summer can actually save lives: research published back in November predicted that if the U.S. stayed on permanent daylight saving time, the decrease in car-versus-deer collisions due to poor evening lighting would save an average of 33 human lives every year (along with over 30,000 deer lives). Staying on permanent standard time, however, would increase the number of collisions. The U.S. legislature is debating a switch to permanent daylight saving time, while several states are considering bills that would move them permanently to either daylight saving or standard time (Hawaii and Arizona are already on permanent standard time).
It could be my sleep deprivation talking, but all of this debate over how we set our clocks is fascinating: on the one hand, it emphasizes how arbitrary our social conception of clock time is— it's just different names for our planet’s orientation relative to the sun. On the other hand, biologists and economists are tugging on the astronomers’ sleeves saying, “Um, actually, our communal decisions about whether sunrise is at 6am or 7am has a measurable effect on our lives.”
Meanwhile, the fundamental question of “What time is it?”— and how we can come to an agreement on the answer— extends into space along with human activity. Mars lander and rover operators match their workdays on Earth to the slightly longer Martian day, called a “sol”, which is 24 hours, 39 minutes, and 35 seconds long. Studies have shown that human test subjects simulating a Martian sol schedule don’t end up adjusting their circadian rhythms to the longer day, suggesting that future residents of Mars may struggle to adjust to the local day/night cycle without the help of light therapy.
Closer to our home planet, the European Space Agency has recently argued that we need a universal timekeeping system for the moon, to improve coordination between missions. But there are still open questions— should lunar time be forced to synchronize with Earth? Should a single organization be responsible for determining lunar time, and if so, who? And do we make sure clocks on the Moon are all keeping the same time, when relativity and the orbital speed of the Moon mean that they run about 56 microseconds slower per day than clocks on Earth?
Figuring out something as basic as time zones in space will be crucial not only for technologies like GPS and appointment calendars, but also for the sleep and health of the humans living there. I hope we can develop unified and evidence-based solutions for space faster than we have here on Earth!
Other News
My book, Off-Earth: Ethical Questions and Quandaries for Living in Outer Space, came out last week! If you preordered a copy, you can submit a screenshot of your receipt on this form and get a free ticket to a live virtual author Q&A with me (hosted by Celestial Citizen’s Britt Duffy Adkins) on Thursday, March 16 at 8pm EDT— that’s Eastern Daylight Time. It’s shaping up to be a good conversation, I hope you can join us.
There was also a nice review of Off-Earth in Ars Technica this week: “Off-Earth will amaze you… [It’s] really, really good.”