Understanding Vocabulary in Context

Consider the following excerpt from a contemporary short story:

As the sun dipped below the horizon, the sky was illuminated in shades of purple and gold, a spectacle that took Maria's breath away. In that moment, she felt a profound sense of serenity, her worries fading into the background like the darkening clouds. It was a perfect ending to a chaotic day, a reminder that beauty could be found even in the small hours of twilight.

What does the word illuminated most closely mean in this context?