Why was Moses' Face Radiant?

Why was the face of Moses “radiant” after he came down from the mountain (Exodus 34:30)?

Some think this radiance was the glory Moses prayed for during his second 40 days (33:18). Others believe that Moses' anger when he first descended the mountain (32:19) canceled out any glory that would have appeared on his face. When Moses descended the second time, he was not angry.

–The Quest Study Bible