The movement of the sun is confirmed in the Brahma-samhita (5.52): yasyajnaya bhramati sambhrtakala- cakrah. In the chariot of the sun-god, the sun travels on the top of the mountain in an orbit called the Samvatsara, encircling Mount Meru. The sun’s path on the northern side is called Uttarayana, and its path on the southern side is called Daksinayana. One side represents a day for the demigods, and the other represents their night. The sun is not stationary; it is also moving like the other planets. The sun’s movements determine the duration of night and day. When the sun travels north of the equator, it moves slowly during the day and very quickly at night, thus increasing the duration of the daytime and decreasing the duration of the night. Similarly, when the sun travels south of the equator, the exact opposite is true–the duration of the day decreases, and the duration of night increases. When the sun enters Karkata-Rasi (Cancer) and then travels to Simha-Rasi (Leo) and so on through Dhanuh-rasi (Sagittarius), its course is called Daksinayana, the southern way, and when the sun enters Makara-Rasi (Capricorn) and thereafter travels through Kumbharasi (Aquarius) and so on through Mithuna-Rasi (Gemini), its course is called Uttarayana, the northern way. When the sun passes through Mesa [Aries] and Tula [Libra], the duration of day and night are equal. When it passes through the five signs headed by Vrsabha [Taurus], the duration of the day’s increases [until Cancer], and then it gradually decreases by half an hour each month until day and night again become equal [in Libra]. When the sun passes through the five signs beginning with Vrscika [Scorpio], the duration of the day’s decreases [until Capricorn], and then gradually it increases month after month, until day and night become equal [in Aries]. Until the sun travels to the south the days grow longer, and until it travels to the north the nights grow longer. The sun travels over all sides of Manasottara Mountain in a circle whose length is 95,100,000 yojanas [760,800,000 miles]. On Manasottara Mountain, due east of Mount Sumeru is a place known as Devadhani, possessed by King Indra. Similarly, in the south is a place known as Samyamani, possessed by Yamaraja, in the west is a place known as Nimlocani, possessed by Varuna, and in the north is a place named Vibhavari, possessed by the moon-god. Sunrise, midday, sunset and midnight occur in all those places according to specific times, thus engaging all living entities in their various occupational duties and also making them cease such duties. The living entities residing on Sumeru Mountain are always very warm, as at midday, because for them the sun is always overhead. Although the sun moves counterclockwise, facing the constellations, with Sumeru Mountain on its left, it also moves clockwise and appears to have the mountain on its right because it is influenced by the daksinavarta wind. People living in countries at points diametrically opposite to where the sun is first seen rising will see the sun setting, and if a straight line were drawn from a point where the sun is at midday, the people in countries at the opposite end of the line would be experiencing midnight. Similarly, if people residing where the sun is setting were to go to countries diametrically opposite, they would not see the sun in the same condition. When the sun travels from Devadhani, the residence of Indra, to Samyamani, the residence of Yamaraja, it travels 23,775,000 yojanas [190,200,000 miles] in fifteen ghatikas [six hours]. The total orbit of the sun is four times that distance, or 95,100,000 yojanas (760,800,000 miles). From the residence of Yamaraja, the sun travels to Nimlocani, the residence of Varuna, from there to Vibhavari, the residence of the moon-god, and from there again to the residence of Indra. In a similar way, the moon, along with the other stars and planets, becomes visible in the celestial sphere and then sets and again becomes invisible. Thus the chariot of the sun-god, which is trayimaya, or worshiped by the words om bhur bhuvah svah, travels through the four residences mentioned above at a speed of 3,400,800 yojanas [27,206,400 miles] in a muhurta. The chariot of the sun-god has only one wheel, which is known as Samvatsara. The twelve months are calculated to be its twelve spokes, the six seasons are the sections of its rim, and the three catur-masya periods are its three-sectioned hub. One side of the axle carrying the wheel rests upon the summit of Mount Sumeru, and the other rests upon Manasottara Mountain. Affixed to the outer end of the axle, the wheel continuously rotates on Manasottara Mountain like the wheel of an oil-pressing machine. As in an oil-pressing machine, this first axle is attached to a second axle, which is one-fourth as long [3,937,500 yojanas, or 31,500,000 miles]. The upper end of this second axle is attached to Dhruvaloka by a rope of wind. The carriage of the sun-god’s chariot is estimated to be 3,600,000 yojanas [28,800,000 miles] long and one-fourth as wide [900,000 yojanas, or 7,200,000 miles]. The chariot’s horses, which are named after Gayatri and other Vedic meters, are harnessed by Arunadeva to a yoke that is also 900,000 yojanas wide. This chariot continuously carries the sun-god. The seven horses yoked to the sun-god’s chariot are named Gayatri, Brhati, Usnik, Jagati, Tristup, Anustup and Pankti. These names of various Vedic meters designate the seven horses that carry the sun-god’s chariot. Although Arunadeva sits in front of the sun-god and is engaged in driving the chariot and controlling the horses, he looks backward toward the sun-god. There are sixty thousand saintly persons named Valikhilyas, each the size of a thumb, who are located in front of the sun-god and who offer him eloquent prayers of glorification. Similarly, fourteen other saints, Gandharvas, Apsaras, Nagas, Yaksas, Raksasas and demigods, who are divided into groups of two, assume different names every month and continuously perform different ritualistic ceremonies to worship the Supreme Lord as the most powerful demigod Suryadeva, who holds many names. Worshiping the most powerful demigod Surya, the Gandharvas sing in front of him, the Apsaras dance before the chariot, the Nisacaras follow the chariot, the Pannagas decorate the chariot, the Yaksas guard the chariot, and the saints called the Valikhilyas to surround the sun-god and offer prayers. The seven groups of fourteen associates arrange the proper times for regular snow, heat, and rain throughout the universe. In his orbit through Bhu-mandala, the sun-god traverses a distance of 95,100,000 yojanas [760,800,000 miles] at the speed of 2,000 yojanas and two krosas [16,004 miles] in a moment.
Source: A.C. Bhaktivedanta Swami Prabhupada (2014 edition), “Srimad Bhagavatam”, Fifth Canto, Chapter 21