The planet probably got this name due to its red color; Mars is sometimes referred to as 'the Red Planet'.
A lot of people call Mars "The Red Planet"
( z1 call :ARG0 ( z2 person :quant ( z3 lot ) ) :ARG1 ( z4 planet :name ( z5 name :op "Mars" ) ) :ARG2 ( z6 planet :name ( z7 name :op "Red" :op "Planet" ) ) )