Why does the space after \AA disappear?
\documentclass{article}
\begin{document}
5 \AA wavelength
\end{document}

Since extra spaces don't achieve anything in LaTeX, what can be done besides forcing a space? Also, why is this symbol causing this affect?
\AA{}, then you don't technically force the space. – Werner May 21 '14 at 21:43siunitxfor units, and the problem will disappear:\SI{5}{\angstrom}– egreg May 21 '14 at 21:58