In EVE everything within 1000km is on the same “grid”. within a solar system you can only warp to known locations. That includes locations that were manually saved or celestial objects like moons and planets.
That means when someone warps to a moon, they can see anyone who warped to that moon, since they are on the same grid.
A safe spot is a location that isn’t on the same grid as a known location. You can still be scanned down by someone, but there are ways to know about it.
Edit: Its been a while and I’m no expert, so anyone feel free to correct me.
Alternative title: “Follow these 17 convoluted steps to stay in your abusive relationship longer.”