Satyaloka, Tapoloka, Janaloka, Maharloka, Suvarloka, Bhuvarloka, Bhuloka, Atala, Vitala, Nitala, Rasatala, Mahatala, Sutala and Patala.
The Puranas usually describe these worlds as different regions of the observable universe (the planet Earth, Earth's immediate neighborhood and regions far beyond). Bhagavata Purana has many passages that describe these worlds as inhabited planets with movement of people between them through some kind of inter planetary travel.
The scholar Deborah Soifer describes the development of the concept of lokas as follows:
The concept of a loka or lokas develops in the Vedic literature. Influenced by the special connotations that a word for space might have for a nomadic people, loka in the Veda did not simply mean place or world, but had a positive valuation: it was a place or position of religious or psychological interest with a special value of function of its own.Hence, inherent in the 'loka' concept in the earliest literature was a double aspect; that is, coexistent with spatiality was a religious or soteriological meaning, which could exist independent of a spatial notion, an 'immaterial' significance.The most common cosmological conception of lokas in the Veda was that of the trailokya or triple world: three worlds consisting of earth, atmosphere or sky, and heaven, making up the universe."
Ancient Indian Astronomers :-
LOKAS IN SHORT -Bhurloka-The sphere of the earth or Bhúr-loka, comprehending its oceans, mountains, and rivers, extends as far as it is illuminated by the rays of the sun and moon; and to the same extent, both in diameter and circumference, the sphere of the sky (Bhuvar-loka) spreads above it (as far upwards as to the planetary sphere, or Swar-loka.Wherever earthy substance exists, which may be traversed by the feet, that constitutes the sphere of the earth (Bhu Loka).‘Bhu’ means ‘Earth’ and ‘loka’ means the surface of planet Earth, where we live.
Bhuvar Loka-The region that extends from the earth to the sun, in which the Siddhas and other celestial beings move, is the atmospheric sphere (Bhuvar Loka). Bhuvar-loka is identified with Earth’s atmosphere and sometimes with the space which is in the immediate neighborhood of Earth.
Suvar Loka- The interval between the sun and Dhruva, extending fourteen hundred thousand leagues, is called by those who are acquainted with the system of the universe the heavenly sphere (Suvar Loka).Suvar-loka (alternatively Swar-loka) is beyond Bhuvarloka.Some description makes it a planet inhabited by the Devas with their king Indra.Some references make it equivalent to the Swarga.Some Puranic references equate Suvarloka to the Solar System.
Maharloka-Above Dhruva, at the distance of ton million leagues, lies the sphere of saints, or Mahar-loka, the inhabitants of which dwell in it throughout a Kalpa, or day of Brahmá.
Janaloka-At twice that distance is situated Janaloka, where Sanandana and other pure-minded sons of Brahmá, reside.
Tapoloka- At four times the distance, between the two last, lies the Tapo-loka (the sphere of penance), inhabited by the deities called Vaibhrájas, who are unconsumable by fire.
Satyaloka-At six times the distance (or twelve Crores, a hundred and twenty millions of leagues) is situated Satya-loka, the sphere of truth, the inhabitants of which never again know death
These three lower spheres are termed transitory: the three highest, Jana, Tapa, and Satya, are styled durable 4: Maharloka, as situated between the two, has also a mixed character; for although it is deserted at the end of the Kalpa, it was not destroyed yet.
Atala- is ruled by Bala - a son of Maya - who possesses mystical powers. By one yawn, Bala created three types of women - svairiṇīs ("self-willed"), who like to marry men from their own group; kāmiṇīs ("lustful"), who marry men from any group, and the puḿścalīs ("those who wholly give themselves up"), who keep changing their partners. When a man enters Atala, these women enchant him and serve him an intoxicating cannabis drink that induces sexual energy in the man. Then, these women enjoy sexual play with the traveller, who feels to be stronger than ten thousand elephants and forgets impending death.
Vitala-is ruled by the god Hara-Bhava - a form of Shiva, who dwells with attendant ganas including ghosts and goblins as the master of gold mines. Here he enjoys sexual union with his consort Bhavani and their sexual fluids flow as river Hataki here. When fire - fanned by wind - drinks from this river, it spits the water out as a type of gold called Hataka. The residents of this realm are adorned with gold from this region.
Sutala- is the kingdom of the pious demon king Mahabali. The dwarf Avatar of Vishnu, Vamana tricked Bali - who had conquered the three worlds - by begging for three paces of land and acquired the three worlds in his three paces. Vamana pushed Bali to Sutala, but when Bali surrendered to Vishnu and gave away all his belongings to him, Vishnu in return made Bali, richer than Indra, the god-king of heaven. Bali still prays to Vishnu in this realm.
Talātala- is the realm of the demon-architect Maya, who is well-versed in sorcery. Shiva, as Tripurantaka, destroyed the three cities of Maya but was later pleased with Maya and gave him this realm and promised to protect him.
Mahātala- is the abode of many-hooded nāgas - the sons of Kadru, headed by the Krodhavasha (Irascible) band of Kuhaka, Taksshaka, Kaliya and Sushena. They live here with their families in peace but always fear garuda.
Rasātala- is the home of the demons - Danavas and Daityas, who are mighty but cruel. They are the eternal foes of Devas (the gods). They live in holes like serpents.
Patala or Nagaloka- is the lowest realm and the region of the Nagas, ruled by Vasuki. Here live several Nagas with many hoods. Each of their hood is decorated by a jewel, the light of which illuminates this realm.
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