What does Aarush mean?
From Sanskrit arusha (आरुष), 'reddish, red of dawn', commonly glossed as 'the first ray of the sun'. The 'red/dawn' sense is the attested one; 'first ray of sun' is the popular reading.
What does Dhruv mean?
From the Sanskrit ध्रुव (dhruva), 'fixed, firm, immovable, constant'; also the name of the Pole Star and of the boy-devotee Dhruva in the Puranas, who became the unwavering North Star.