Now you can keep track of what time of day it is at the Mars Rover landing sites. A Martian day is very close to an Earth day --- about 24 Earth hours plus 39-1/2 minutes. This means a normal quartz clock can't keep Martian time. We have created a quartz clock with a timebase adjusted to conform to mean Mars time. The clock divides the Martian day into 24 hours. Once you have set the clock to the local Mars time at one of the Mars Rover locations, you can tell at a glance what time of Martian day it is for the rovers.
So each hour is 1.65 minutes longer than an Earth hour? Interesting.