Is telling a falsehood always a lie?

Alright, do you see lying as to communicate deliberately what you don’t believe, or to communicate deliberately what isn’t true? So in other words, is it a lie for someone to unwittingly pass on false information, or are they not lying because they genuinely believe it? My view on it is that if I were told that Mercury was the hottest planet (a falsehood) and believed it, then told someone, I wouldn’t be lying, even though I’d been misinformed? Is that the consensus, or would people instead say that lying is based on whether or not something is actually “true” and that I had actually unwittingly lied? Doesn’t really make sense to me that unwittingly lying is a thing, because one does believe it and isn’t trying to deceive.