To maintain observe of time on the Purple Planet, astronomers use a Mars clock with 24 “Mars hours” based mostly on the planet’s rotation.
This composite, that includes two photographs taken by the Curiosity rover, exhibits views on April 8, 2023, at 9:20 a.m. (proper) and three:40 p.m. (left) native Mars time. Credit score: NASA/JPL-Caltech
What’s “native martian time”?
Dennis W. Gordon
Waunakee, Wisconsin
Mars doesn’t but have an official calendar or time zones like now we have on Earth. The one formally designated time unit on the Purple Planet is the sol, which is outlined just like the day is on Earth: one full planetary rotation on its axis. However for planning and knowledge evaluation, scientists and engineers engaged on Mars missions nonetheless want a way to determine what time it’s, not right here on Earth, however there at a selected place on that planet. So, identical to on Earth, we will divide a martian sol into totally different time zones — native martian occasions, if you’ll.
In an effort to hold Mars time acquainted to these of us again on Earth, one can tally time on every sol utilizing a Mars clock with 24 “Mars hours.” These Mars hours are sometimes known as “solar hours” as a result of they observe the Solar’s place within the Purple Planet’s sky. For instance, 12:00 midday native Mars time is when the Solar is highest within the sky at that particular place. A brand new sol begins at 12:00 midnight native Mars (solar) time.
As a result of Mars rotates on its axis just a bit bit slower than Earth does, although, a sol on Mars is 2.75 p.c longer than a day on Earth: 24 hours 39 minutes 35 seconds. So expressed in Earth time, on Mars every solar hour is 1 hour 1 minute 39 seconds (1/24 of a sol) lengthy, every solar minute is 61.65 seconds lengthy, and every solar second is 1.0275 seconds lengthy.
This small distinction makes life difficult for these of us again on Earth dwelling on “Mars time” vicariously via our lander and rover avatars. For instance, if we have to begin rover operations three hours after native dawn each sol, and we begin at midday Earth time on a Monday, we’ll begin round 12:37 P.M. on Tuesday, then 1:15 P.M. on Wednesday, 1:52 P.M. on Thursday, and many others. Inside a couple of weeks, we’re working late-night shifts (Earth time), after which a couple of weeks later we’re again into common workday hours. It’s complicated and physiologically difficult to dwell on Earth and work on native martian time — but in addition nice enjoyable!
Jim Bell
Deputy Principal Investigator for Science for the Mars Science Laboratory Mastcam, Arizona State College, Tempe, Arizona
