Warning: Your reality is out of date

tl;dr:

There are established facts that don't change perceptibly (the boiling point of water), and there are facts that change constantly (outside temperature, time of day)

Inbetween these two intuitive categories, however, a third class of facts could be defined: facts that do change measurably, or even drastically, over human lifespans, but still so slowly that people, after first learning about them, have a tendency of dumping them into the "no-change" category unless they're actively paying attention to the field in question.

Examples of these so-called mesofacts include the total human population (6*10⁹? No, almost 7*10⁹ nowadays) and the number of exoplanets found (A hundred? Two hundred? More like four hundred and counting.)