The sun that rose crooked (Ravana, Surya and the first Vishu)
Kerala says that while Ravana ruled Lanka he would not let the sun rise straight in the east; the morning after Rama killed him the sun rose due east again, and that sunrise was the first Vishu. Valmiki's Ramayana gives the root: a Ravana who forestalls the rising of sun and moon, the sun urging Rama on, and a sun that shines steady at Ravana's fall.
While Ravana ruled Lanka he did not allow Surya to rise straight from the east; the sun rose at a slant. After Ravana's death, which Kerala tellers lay to Rama, the sun began to rise straight from the east again, and the first such morning was Vishu. Hindus of Kerala keep Vishu to mark the sun's return, seeing the kani at dawn. The Annapoorneshwari temple of Cherukunnu in Kannur keeps the belief with its Vishu Vilakku. Beside it Kerala keeps the reading that Krishna killed Narakasura on the same day, and both are accepted.
When Shurpanakha reaches Lanka the poet describes Ravana: ten necks, twenty arms, scars from Indra's bolt and Airavata's tusks, conqueror of Kubera who took Pushpaka and tore up Nandana, and the one who with his arms forestalls the rising of the moon and the sun; after ten thousand years of penance Brahma made him safe from gods, demons and spirits, excepting men. On the last day of the war Agastya teaches the weary Rama the Aditya Hridaya, the hymn to the sun; Rama sips water three times, faces the sun and recites it, and the sun, standing among the gods, urges him to hurry. On Matali's word Rama fires Brahma's arrow into Ravana's chest; he falls like Vritra, drums sound, flowers fall, the quarters brighten, the earth stills, the wind softens and the sun shines steadily.
What is different here:
No crooked sunrise and no Vishu: the epic gives Ravana power over the sun's rising, the sun's blessing on Rama, and a steady sun at Ravana's fall.
Sources: Vishu Vilakku at the Annapoorneshwari temple, Cherukunnu, Kannur (Kerala Tourism, 1000 festivals record); Vishu, Wikipedia; Vishu: Regional New Year in Kerala, Utsavpedia; Kerala Vishu, keralafolklore.com; Waking up to Vishu, Amar Chitra Katha (blog); Vishu 2023, Malayalam New Year: history, significance, The Quint; Valmiki Ramayana, Aranya Kanda sarga 32 (valmikiramayan.net, English with verse glosses); Valmiki Ramayana, Yuddha Kanda sarga 105, the Aditya Hridaya (valmikiramayan.net)