Ursula is an asteroid 216 kilometers in diameter. It will need to be hollowed out to create a terrarium.
Each one of Renee’s 3,021 followers can have 7.15 hectares of land on the inside surface.
One year on Ursula lasts 2,018 Earth days.
One day on Ursula lasts 4 minutes.
That creates a centrifugal force of 9.50 gees on the interior.
Decrease the speed of rotation to 11 minutes for Earth-like gravity.