We would like to start by stating that ‘SOL’ can mean a number of things and what it is aimed at suggesting depends on the context in which it is being used. It can be an abbreviation for a common term that we all use, or it can be used to refer to a star.
It Means Our Sun
You might be amused to know that ‘Sol’ is derived from a Latin word, ‘Solis’ which is the name of our sun. Some people might even say that it is the proper name of our sun but in the modern world, you won’t hear NASA scientist referring to the star of our solar system with that name. However, if you are a Spanish, Swedish or a French astronomer speaking in your mother tongue, then you might be using it as in these languages Sol translates to the sun.
It’s A Day On Mars
Though you may not hear people from NASA using ‘sol’ for our sun is because they have their meaning for the term. Yes, in the world of astronomy, ‘sol’ is short of the solar day, or the time that the planet Mars takes to complete one revolution around its axis. One day on Mars is 24 hours 37 minute 22.663 seconds long, which is about 2.7 percent longer than what we have here on earth. The spacecraft going to Mars are equipped with special clocks that help in keeping track of the local time.
Source: What Does SOL Mean?