kecana — some yogīs or learned scholars of astronomy; etat — this; jyotiḥ-anīkam — great wheel of planets and stars; śiśumāra-saṁsthānena — imagine this wheel to be a śiśumāra (dolphin); bhagavataḥ — of the Supreme Personality of Godhead; vāsudevasya — Lord Vāsudeva (the son of Vasudeva), Kṛṣṇa; yoga-dhāraṇāyām — in absorption in worship; anuvarṇayanti — describe.
This great machine, consisting of the stars and planets, resembles the form of a śiśumāra [dolphin] in the water. It is sometimes considered an incarnation of Kṛṣṇa, Vāsudeva. Great yogīs meditate upon Vāsudeva in this form because it is actually visible.
Transcendentalists such as yogīs whose minds cannot accommodate the form of the Lord prefer to visualize something very great, such as the virāṭ-puruṣa. Therefore some yogīs contemplate this imaginary śiśumāra to be swimming in the sky the way a dolphin swims in water. They meditate upon it as the virāṭ-rūpa, the gigantic form of the Supreme Personality of Godhead.