The Season of the Wish takes Destiny 2 players back to the Dreaming City for the first time since before the launch of The Witch Queen and resurrects some major elements from way back in the Forsaken expansion. One of those things is the quest to find cosmic kitties hiding within the Dreaming City. It seems that each week during the Season of the Wish, new Starcats will appear within the city, requiring you to track them down to unlock Triumphs and earn some specific rewards.
Locating all the Starcats is essential to complete the Wishbearer seal and will also earn you the Wyrmguard Shell for your Ghost.