I have tried at least 4 different pets of 3 different species and one had no stars while the other three did and all 4 in showed the whole island instead of just a little bit at a time in 3 different terrains, Tundra, Volcano, and Savannah.  Not complaining, but you do need to know about it.

If you have an inn built there is a guest called a Travelling Magician that will remove the Fog of War (black squares that are revealed as you move) from islands in explore. Guests at the inn stay for three days. If he’s staying at your Inn then it’s not a bug. To check, go to Manor -> Buildings -> Inn, it should say who’s at the inn.

Thank you.  I've only been playing about 6 weeks now so I didn't know.