In 1868, an atlas of the solar spectrum was published, unveiling measurements of about a thousand spectral lines with unprecedented accuracy. The author of this atlas, the Swedish physicist Anders Jonas Ångström, had to introduce a new unit of measurement for this, which was later named after him. Ångström became one of the founders of spectroscopy and became famous in the academic community as a researcher of the solar and auroral spectrum. He then became known to all physicists, chemists and biologists, as well as those who still had scientific careers ahead of them and even those who were distant from it, but still studied in school thanks to the smallest unit of length. The letter “Å,” that is, the Swedish letter with which Ångström’s last name begins, means a unit of length equal to one ten-billionth of a meter. This is the approximate diameter of the electron orbit in a non-excited atom of hydrogen.