"Lord let me shine, shine like the moon,
A reflection of You in all that I do.
Lord let me be a light for Your truth;
Light of the world, I wanna be used to shine for You."
These planets (and the moon) emit no light by themselves. But being in the presence of the sun transforms them into reflectors of its magnificent glory -
"And we, who with unveiled faces all reflect the Lord’s glory, are being transformed into his likeness with ever-increasing glory, which comes from the Lord, who is the Spirit."
2 Corinthians 3:18