I should call her

Yeah the fact it's called a small moon is slightly deceptive to us because our moon is absolutely huge as far as moons go. The natives of the SW universe would be used to much much smaller moons.

For reference, our moon is 3475km across and the death star is 150km across, so it's diameter is 23 smaller. It's also weighed at about 900million tonnes or 9*10^14kg.

If I'm right (which I'm likely not). g=(GM)/r² or g=(6.66710^-119*10^13)/75².

That's a gravity of 1.086x10^-5m/s² or if I round with pure disrespect for physics, 100,000 times weaker than earth's gravity. Essentially it's totally negligible compared to their artificial gravity. Hell, I don't even think a marble on the floor would overcome it's own grip and roll towards the center of the space station.

My maths is almost certainly wrong somewhere here, I failed it badly.

So small that a natural body of that size probably wouldn't be massive enough to hold a spherical shape. DS1 was a little smaller than the real asteroid 128 Nemesis, which isn't spherical. Maybe if it were made of something extremely dense, it would be, but you're not likely to find a natural spherical object that size.

Now that I think of it, this puts the "that's no moon" scene in perspective. Luke is a country bumpkin who just calls it a moon, but Obi-wan has an idea of its size (perhaps from glancing at the Falcon's scans, since size and distance is hard to judge by eye; or he's just a space wizard), and knows a natural object couldn't be that spherical.