yavad avabhasayati sura-girim anuparikraman bhagavan adityo vasudha-talam ardhenaiva pratapaty ardhenavacchadayati tada hi bhagavad-upasanopacitati-purusa-prabhavas tad anabhinandan samajavena rathena jyotirmayena rajanim api dinam karisyamiti sapta-krt vastaranim anuparyakramad dvitiya iva patangah.
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
While so excellently ruling the universe, King Priyavrata once became dissatisfied with the circumambulation of the most powerful sun-god. Encircling Sumeru Hill on his chariot, the sun-god illuminates all the surrounding planetary systems. However, when the sun is on the northern side of the hill, the south receives less light, and when the sun is in the south, the north receives less. King Priyavrata disliked this situation and therefore decided to make daylight in the part of the universe where there was night. He followed the orbit of the sun-god on a brilliant chariot and thus fulfilled his desire. He could perform such wonderful activities because of the power he had achieved by worshiping the Supreme Personality of Godhead.
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
There is a Bengali saying which describes that someone is so powerful that he can make the night day and the day night. That saying is current because of the prowess of Priyavrata. His activities demonstrate how powerful he became by worshiping the Supreme Personality of Godhead. Lord Krsna is known as Yogesvara, the master of all mystic powers. In Bhagavad-gita (18.78) it is said wherever there is the master of all mystic powers (yatra yogesvarah krsnah), victory, fortune and all other opulences are present. Devotional service is so powerful. When a devotee achieves what he wants to accomplish, it is not by his own mystic power but by the grace of the master of mystic power, Lord Krsna: by His grace, a devotee can accomplish wonderful things unimaginable even to the most powerful scientist.
From the description in this verse, it appears that the sun moves. According to modern astronomers, the sun is fixed in one place, surrounded by the solar system, but here we find that the sun is not stationary: it is rotating in a prescribed orbit. This fact is corroborated by Brahma-samhita (5.52). Yasyajñaya bhramati sambhrta-kala-cakrah: the sun is rotating in its fixed orbit in accordance with the order of the Supreme Personality of Godhead. According to Jyotir Veda, the science of astronomy in the Vedic literature, the sun moves for six months on the northern side of the Sumeru Hill and for six months on the southern side. We have practical experience on this planet that when there is summer in the north there is winter in the south and vice versa. Modern materialistic scientists sometimes present themselves as knowing all the ingredients of the sun, yet they are unable to offer a second sun like Maharaja Priyavrata’s.
Although Maharaja Priyavrata devised a very powerful chariot as brilliant as the sun, he had no desire to compete with the sun-god, for a Vaisnava never wants to supersede another Vaisnava. His purpose was to give abundant benefits in material existence. Srila Visvanatha Cakravarti Thakura remarks that in the months of April and May the rays of Maharaja Priyavrata’s brilliant sun were as pleasing as the rays of the moon, and in October and November, both morning and evening, that sun provided more warmth than the sunshine. In short, Maharaja Priyavrata was extremely powerful, and his actions extended his power in all directions.