• Mars Date/Time:  Year 1, Sur One, Sol 23 (1.1.23)  4:54 PM NST
• Earth Date/Time:  26 January 2016  2:00 PM PST

It is important to remember that a calendar is a human device, not a scientific one. Humans have divided time into units in order to keep track of the past, present, and future events, and science has worked to make time units more precisely measured. Thus, creating time units for Mars is to establish the standard for humans to use to reference past, present, and future events.

There are many possible ways to establish time units on Mars, but the Earth Space Exploration Program (ESEP) determined that fusing elements of Earth time units with the characteristics of Mars would be the most efficient. 

An Earth Day is defined by one rotation of the planet

DAY
One Earth day is based on one rotation of our planet. It is divided into 24 increments, called hours. Hours are divided into 60 minutes, and minutes are divided into 60 seconds.

One Mars day is also based on one rotation of the planet; however, compared to Earth, Mars rotation takes approximately 24 hours and 40 minutes. Because it is so close, and we are accustomed to the 24 hour clock, scientists have established a “Mars clock” that also has a 24 hour day. They did this by making each second of Mars time slightly longer than an Earth ‘second,’ so there are still 60 seconds to a Mars minute, and 60 minutes to a Mars hour, and 24 hours to a Mars day.

A Mars Day is about 40 minutes longer than Earth’s

However, this makes a Mars day out of sync with an Earth day, but that is unavoidable. Earth rotates faster than Mars, therefore, Earth days occur faster than Mars.