The wikipedia article https://en.wikipedia.org/wiki/Angstrom https://en.wikipedia.org/wiki/Angstrom has some historical context: 'In the late 19th century, spe

The wikipedia article https://en.wikipedia.org/wiki/Angstrom https://en.wikipedia.org/wiki/Angstrom has some historical context: 'In the late 19th century, spectroscopists adopted 10^−10 of a metre as a convenient unit (...). However, they soon realized that the definition of the metre at the time, based on a material artifact, was not accurate enough for their work. So, around 1907 they defined their own unit of length, which they called "Ångström", based on the wavelength of a specific spectral line. It was only in 1960, when the metre was redefined in the same way, that the angstrom became again equal to 10^−10 meter.'