N-O bonds in Nitric acid

The wikipedia article on nitric acid mentions the following structure of $$\ce{HNO3}$$ in which the two $$\ce{N-O}$$ bonds (other than that of $$\ce{N-OH}$$) are of different length i.e., $$119.9\,\pu{pm}$$ and $$121.1\,\pu{pm}$$.

But it also mentions that $$\ce{HNO3}$$ molecule is a resonance hybrid of - (only major contributing ones)

I can't understand how can both be simultaneously correct since the resonance hydrid should have same two $$\ce{N-O}$$ bond lengths (other than $$\ce{N-OH}$$ one). How is it correct or is the source itself wrong?

• The difference is very minor, such minor differences may be caused by multiple very weak effects rarely significant and consequently rarely discussed and explained. Generally it is expected to have unequal bonds (i.e. not transformed into each other by symmetry transformation) to have slightly different length. Specifically, at least 2 effects may be involved here: 1) effect of charge distribution. Significant polarity of O-H bond makes resonance hybrids unequal in energy, so one has higher impact 2) the unconjugated lone pair of OH oxygen can conjugate with only one another N-O bond. Apr 16, 2016 at 6:56