Yoga Sutras of Patanjali 3.29

ध्रुवे तद्गतिज्ञानम् ॥

dhruve tad-gati-jnanam

By samyama on the pole star, knowledge of the movement of the stars arises.

ध्रुव पर (संयम से) उनकी गति का ज्ञान।