When Priyavrata drove his chariot behind the sun, the rims of his chariot wheels created impressions that later became seven oceans, dividing the planetary system known as Bhū-maṇḍala into seven islands.
Sometimes the planets in outer space are called islands. We have experience of various types of islands in the ocean, and similarly the various planets, divided into fourteen lokas, are islands in the ocean of space. As Priyavrata drove his chariot behind the sun, he created seven different types of oceans and planetary systems, which altogether are known as Bhū-maṇḍala, or Bhūloka. In the Gāyatrī mantra, we chant, oṁ bhūr bhuvaḥ svaḥ tat savitur vareṇyam. Above the Bhūloka planetary system is Bhuvarloka, and above that is Svargaloka, the heavenly planetary system. All these planetary systems are controlled by Savitā, the sun-god. By chanting the Gāyatrī mantra just after rising early in the morning, one worships the sun-god.
(Srimad Bhagavatam------5:1:31------purport).

While describing the character of Mahārāja Priyavrata and his descendants, Śukadeva Gosvāmī also described Meru Mountain and the planetary system known as Bhū-maṇḍala. Bhū-maṇḍala is like a lotus flower, and its seven islands are compared to the whorl of the lotus. The place known as Jambūdvīpa is in the middle of that whorl. In Jambūdvīpa there is a mountain known as Sumeru, which is made of solid gold.
(Srimad Bhagavatam------5:16-----summary).

In this verse it is stated that the planetary system known as Bhū-maṇḍala extends to the limits of the sunshine. According to modern science, the sunshine reaches earth from a distance of 93,000,000 miles. If we calculate according to this modern information, 93,000,000 miles can be considered the radius of Bhū-maṇḍala. In the Gāyatrī mantra, we chant oṁ bhūr bhuvaḥ svaḥ. The word bhūr refers to Bhū-maṇḍala. Tat savitur vareṇyam: the sunshine spreads throughout Bhū-maṇḍala. Therefore the sun is worshipable. The stars, which are known as nakṣatra, are not different suns, as modern astronomers suppose. From Bhagavad-gītā (10.21) we understand that the stars are similar to the moon (nakṣatrāṇām ahaṁ śaśī).
(Srimad Bhagavatam------5:16:1------purport).

My dear Lord, the rolling wheels of Mahārāja Priyavrata's chariot created seven ditches, in which the seven oceans came into existence. Because of these seven oceans, Bhū-maṇḍala is divided into seven islands. You have given a very general description of their measurement, names and characteristics. Now I wish to know of them in detail. Kindly fulfill my desire.
(Srimad Bhagavatam------5:16:2------translation).

The great ṛṣi Śukadeva Gosvāmī said: My dear King, there is no limit to the expansion of the Supreme Personality of Godhead's material energy. This material world is a transformation of the material qualities (sattva-guṇa, rajo-guṇa and tamo-guṇa), yet no one could possibly explain it perfectly, even in a lifetime as long as that of Brahmā No one in the material world is perfect, and an imperfect person could not describe this material universe accurately, even after continued speculation. O King, I shall nevertheless try to explain to you the principal regions, such as Bhū-goloka (Bhūloka), with their names, forms, measurements and various symptoms.
(Srimad Bhagavatam------5:16:4------translation).

The planetary system known as Bhū-maṇḍala resembles a lotus flower, and its seven islands resemble the whorl of that flower. The length and breadth of the island known as Jambūdvīpa, which is situated in the middle of the whorl, are one million yojanas (eight million miles). Jambūdvīpa is round like the leaf of a lotus flower.
(Srimad Bhagavatam------5:16:5------translation).

Amidst these divisions, or varṣas, is the varṣa named Ilāvṛta, which is situated in the middle of the whorl of the lotus. Within Ilāvṛta-varṣa is Sumeru Mountain, which is made of gold. Sumeru Mountain is like the pericarp of the lotuslike Bhū-maṇḍala planetary system. The mountain's height is the same as the width of Jambūdvīpa—or, in other words, 100,000 yojanas (800,000 miles). Of that, 16,000 yojanas (128,000 miles) are within the earth, and therefore the mountain's height above the earth is 84,000 yojanas (672,000 miles). The mountain's width is 32,000 yojanas (256,000 miles) at its summit and 16,000 yojanas at its base.
(Srimad Bhagavatam------5:16:7------translation).

My dear King, in his orbit through Bhū-maṇḍala, the sun-god traverses a distance of 95,100,000 yojanas (760,800,000 miles) at the speed of 2,000 yojanas and two krośas (16,004 miles) in a moment.
(Srimad Bhagavatam------5:21:19------translation).

The great sage Śukadeva Gosvāmī answered: All the hellish planets are situated in the intermediate space between the three worlds and the Garbhodaka Ocean. They lie on the southern side of the universe, beneath Bhū-maṇḍala, and slightly above the water of the Garbhodaka Ocean. Pitṛloka is also located in this region between the Garbhodaka Ocean and the lower planetary systems. All the residents of Pitṛloka, headed by Agniṣvāttā, meditate in great samādhi on the Supreme Personality of Godhead and always wish their families well.
(Srimad Bhagavatam------5:26:5------translation).