taru-adjective, adverb taking the 'to' particle
Describes sunlight or light shining brilliantly and warmly. Often used in literary or poetic descriptions of the sun.
さんさんと太陽が降り注ぐ。
The sun shines down brilliantly.
さんさんたる陽光の下でピクニックを楽しんだ。
We enjoyed a picnic under the brilliant sunshine.
Rarely used kanji form.
Rarely used kanji form.
きらきら describes a sparkling or glittering light, often for stars, jewels, or reflections, while さんさん is specifically for strong, warm, brilliant light like sunshine.
まぶしい is an adjective meaning 'dazzling' or 'glaring', often with a nuance of being too bright for the eyes, whereas さんさん is a more poetic, positive brilliance.
Reduplication of the kanji 燦 (brilliant), with the reading さん. The exact origin is uncertain, but it follows a common pattern of forming adverbs or adjectives through reduplication.