Marthanda is a manifestation of Surya, the sun god in Hinduism. Please note that quite often Marthanda is also equated with sun (is another name of Surya). Legend has it that Aditi, the wife of Sage Kashyapa, was serving food to her husband. Suddenly a guest came. Aditi could only attend the guest after she had served her husband.
Aditi Devo Bhava – Guest is considered as God in Hindu culture. The delay in attending to him angered the guest. The guest, in a fit of anger, cursed Aditi that she would abort her fetus.
But Sage Kashyapa saved the fetus. The child that was born was Martanda, the one resurrected from the aborted fetus.