Something effulgent radiates light. On a clear day the sun can be quite effulgent. You might need a pair of shades.
Effulgent comes from the Latin ex meaning "out" and fulgere meaning "to shine". A light that is effulgent, shines out or radiates. A personality that is effulgent radiates warmth and goodness. When you're in love, you have an effulgent or radiant look, as though sunlight were shining from your eyes.