He was a pioneer, in 1853, to observe and study the spectrum of hydrogen which was the foundation for Balmerīs formula.
After leaving the observatory for the professorship in physics at Uppsala university (1858-1874) he continued his spectral research.
In 1867 he was the first to examine the spectrum of aurora borealis (northern lights).
He published his extensive research on the solar spectrum in the classic work "Recherches sur le spectre solaire" (1868),
with detailed measurements of more than 1000 spectral lines.
He also published works on thermal theory and carried out geomagnetical measurements in different places around Sweden.

The Angstrom unit (1A=0.1nm), used in spectroscopy and for measurements on atomic scales, is named in his honour.

More information from the Ångström Laboratory at Uppsala university.