Patanjali Yoga Sutra -ध्रुवे तद्गतिज्ञानम् ॥3.29॥

dhruve tadgatijñānam॥

Through saṁyama on dhruva — the Pole star, the yogi gets the knowledge of the movement of cosmic bodies.

According to Bhāgavata Purāṇam (Caturtha Skandhaḥ — 8th to 13th Adhyāyas) prince, Dhruva was the son of king Uttānapāda and his first queen sunīti. On being denied by his stepmother suruchi, the privilege of sitting on the lap of his father, frustrated Dhruva goes to the forest for austerity (Tapas), on the advice of his mother sunīti. On his way to the forest, he meets Nārada Maharṣi, who initiates him the sacred Dvādaśākṣara stotram (12 lettered sacred phrase) ॐ नमो भगवते वासुदेवाय (AUM namo Bhagavate vāsudevāya — ‘My humble homages to Śrīkr̥ṣṇa, son of Vāsudeva’). Dhruva keeps chanting this sacred Dvādaśākṣara stotram and performs strict austerities and was able to get the darśan (vision) of Lord Nārāyaṇa, who blesses him with a permanent seat in the cosmos, besides fulfilling all his desires. Lord Nārāyaṇa says, ‘So far, no one has been blessed with such an everlasting place in this creation. This interminable place in the universe you are getting remains incessant even when all the worlds are annihilated during ‘Mahāpralaya’. Your eternal Dhruvaloka will be circumambulated even by Dharma, Agni, Kaśyapa, śukra, and other planets and stars.’ That is the pole star, dhruva Nakṣatram. Though being a distant star, dhruva Nakṣatram, guides the sea voyagers like a mariners’ compass.