New ask Hacker News story: Ask HN: Why does a mirror show you back to front but not upside down?

Ask HN: Why does a mirror show you back to front but not upside down?
6 by dave_sid | 5 comments on Hacker News.
Even if you lie down sideways and look at the mirror it still doesn’t flip you upside down, only sideways. Unless you stand on a mirrored floor, in which case it makes you upside down.... but facing forward. What’s going on?