When we are unable to see a distant object, then it is due to one of these reasons:
- Our eyes lack the sufficient angular resolution to recognize the object.
- Atmospheric condition limits visibility.
- The object is far enough and obscured by Earth’s curvature.
Some flat-Earthers like to show that a previously unseen distant object can be brought into view using infrared vision. They would take that as ‘evidence’ of the non-existence of Earth’s curvature. They are wrong. Infrared vision can reveal hidden objects caused by visibility limitations, but not ones obscured by Earth’s curvature.