Look, I don't want to be rude, and I definitely don't want to belittle women.
But when a subject comes up that I know something about, I just have this uncontrollable urge to share my knowledge.
Even if it then turns out that I'm trying to explain the principle of a programming language to Grace Hopper.
Because there comes a moment where the explanation invariably have to speak about the limits of the known universe, usually after some sky related question
As a young child my father got very excited when I asked why the sky was blue. I hadn’t realized he was an optical engineer or that that was what kind of question I’d asked. But I remembered the term Rayleigh scattering
That's pretty much the opposite of mansplaining.
Mansplaining is when you're talking condescendingly to someone, while mistakenly assuming you have superior knowledge.
If that someone has asked you "Why?", or any question for that matter, then you'd need to start explaining something completely unrelated, in order to mansplain.
Honestly, I've read a psychological study on this that basically concluded the it should be called "dadsplaining" because it's based in a natural instinct of wanting to explain things to help your kids grow.