The phrase "light up on" has numerous synonyms including "illuminate" which means to light up or brighten something, "enlighten" which means to provide knowledge or understanding, "shine on" which means to emit or reflect light, and "gleam" which means to shine brightly. Other synonyms include "flash" which means to brighten suddenly or momentarily, "sparkle" which means to emit small bursts of light, and "glimmer" which means to shine faintly. All these synonyms can be used interchangeably with "light up on" to provide variety and enhance creativity in writing and speaking.