Visibility Is Not the Same as Existence

The aurora is not equally visible from every place and at every time.

Its visibility depends on conditions of observation.

That simple fact supports a useful distinction.

Not visible from here is not the same statement as does not exist.

The difference matters far beyond astronomy.

A pattern may be obvious in one dataset and hidden in another.

A person's ability may appear in one environment and disappear in another.

A problem can become visible only when the right measurement exists.

An idea can remain unintelligible until someone has the vocabulary needed to distinguish it.

None of this proves that every invisible thing is real.

That would reverse the mistake.

The point is narrower.

Observation has conditions.

Before turning absence of observation into evidence of absence, ask whether the phenomenon should have been observable from this position, at this time, with these tools.

Perspective can limit what appears.

Reality is not obligated to fit inside the current field of view.