Mars lights?

I know where the mars lights are located on the locomotives but the only info i can find is the colors they came in and who built them, what was their purpose, i know its a light that mounts above the main light of a steam engine but what was it for? and what did the different colors stand for? I know these questions may seem rather simplistic but as i said before im rather new to train world and dont know much, when looking at old steam engine photos and my own model trains i like knowing what the different parts are and why they do what they do. Thanks agian for all the help, im sure this wont be my last questoin

The Mars light mounted on the motive power units starting in the mid-1930s was primarily a safety measure. Many railroads speeded up their passenger trains at that time and the Mars light was to call attention to a high speed train. It rotated in a figure 8 pattern. As an example, CBQ introduced a Denver Zephyr about 1936 on a 16-hour Denver-Chicago timing replacing a heavyweight train that took about 24 hours over the same route. Find one of those S. Kip Farrington books, Railroading from the Head End, Railroading from the Rear End, Railroads of Today, Railroads of the Hour and more and you'll find text on the Mars lights and photos. Col. Farrington had access to top managers of many railroads and his books are practically p. r. pieces to those roads and their activities.

Wasn't the Mars light the one that rotated, the beam being slightly off from center?

Anyway, Mars lights, and figure-eight lights, and later beacons, strobes, and ditch lights were for extra visibility to get your attention.

Some roads carried red Mars lights on the front end. I'm told that they would be activated in the event that a train was stopped, to give approaching trains an early warning. Wasn't it CB&Q who had those?

I read that sometimes, the rotating type Mars light would put the engine crew to sleep at night...the light image ahead going slowly round and round and round.