Google’s homepage today honours a Swedish physicist considered to be one of the founders of spectroscopy, on the 200th anniversary of his birth.
Anders Jonas Ångström was born on 13 August 1814 in Medelpad, Sweden. He later moved to Uppsala, where he was educated in physics at Uppsala University.
In 1853, Ångström pointed out to the Royal Swedish Academy of Sciences how the electric spark yields two superposed spectra, one from the metal of the electrode and the other from the gas in which it passes. It was for this long-overlooked observation that he was recognised as one of the founders of spectroscopy, the study of the interaction between matter and radiated energy, by Sir Edward Sabine when awarding him the Rumford medal in 1872.
In its early days, spectroscopy involved the study of visible light dispersed according to its wavelength via a prism and, in today’s stylised logo on the Google homepage, Ångström is depicted studying these wavelengths in terms of the unit that bears his name.
The ångström unit, where 1Å is equal to one 10-billionth of a metre, has been used to measure atoms, molecules, microscopic biological structures, the lengths of chemical bonds, the arrangement of atoms in crystals, the dimensions of integrated circuit parts and, of course, the wavelengths of electromagnetic radiation.
In 1862, Ångström combined the spectroscope with photography and proved that the sun’s atmosphere contained hydrogen and his map of the normal solar spectrum published in 1868, detailing measurements of more than 1,000 spectral lines, was an authoritative reference on wavelengths for a lengthy period.
In 1867, Ångström became the first person to examine the spectrum of the aurora borealis, and the characteristic bright line in its yellow-green region is often called by his name. He also shares his name with a crater on the moon and a laboratory at Uppsala University.
Ångström died on 21 June 1874.