LUNA COLONY IRIS 

The Iris is a station on the moon so large it can be seen from Earth, boasting everything from high-end laboratories to luxury hotels. The facility houses millions of people who live life not too dissimilar from that on Earth, with ordinary jobs and hobbies. While far from the majority, a large portion of the populous are involved in some capacity with the ever-expanding mining industry. 

The first occupants were, of course, originally from Earth, though once having spent extended time on the Iris it can be incredibly difficult to return to their home planet due to the vast gravity disparity. People born on Iris, colloquially known as grommets or often groms, develop bodies accustomed only to the low gravity, and require intense training to visit Earth even for a short time.