The antonyms for the phrase "becoming dark" are "lightening up," "brightening," and "illuminating." These words convey the opposite meaning of the initial phrase, which suggests a gradual dimming or loss of light. To "lighten up" implies an increase in brightness, while "brightening" suggests a sudden burst of light or a quick change in lighting conditions. "Illuminating" refers to the act of shedding light on a subject, whether through a literal illumination or a figurative understanding. These antonyms convey a sense of hope, optimism, and positivity that is often absent from descriptions of darkness, and they remind us that even the darkest moments can be illuminated by a glimmer of light.