Anders Jonas Angström

Anders Jonas Ångström (Swedish pronunciation: /ˈânːdɛʂ ˈjûːnas ˈɔ̂ŋːstrœm/; Lögdö, Sweden, August 13, 1814-Uppsala, Sweden, June 21, 1874) was a Swedish physicist and astronomer, considered one of the founders of the science of spectroscopy.

Biography

Ångström was born in Lögdö, Sweden, on August 13, 1814, and studied at the University of Uppsala, where in 1839 he became a professor of physics. In 1842 he transferred to the Stockholm Observatory to gain practical experience in astronomy and the following year he was appointed keeper of the Uppsala Astronomical Observatory.

Begins to be interested in magnetism and makes many observations of the intensity and decline of terrestrial magnetism at various locations in Sweden. He was commissioned by the Royal Swedish Academy of Sciences to analyze data on the magnetic field obtained by the Swedish frigate Eugénie on her voyage around the world between 1851 and 1853, although he would not finish said work before his death.

In 1858 he succeeded Adolph Ferdinand Svanberg as director of physics at Uppsala. His most important work was related to heat conduction and spectroscopy. In his research on optics, Optiska Undersökningar, presented to the Royal Swedish Academy of Sciences in 1853, he noted not only that an electric spark produced two superimposed spectra, one of the metal electrode and one of the gas by the one that passed, but deduced from Leonhard Euler's theory of resonance that an incandescent gas emitted light rays with the same wavelength as those it could absorb. This statement, as Edward Sabine remarked at the awarding of the Royal Society's Rumford Medal in 1872, contained the fundamental principle of light spectrum analysis, and though it was overlooked for some years, elevates him to the rank of founder of spectroscopy..

He developed a method for measuring thermal conductivity by showing that it was proportional to electrical conductivity.

From 1861 he paid special attention to the solar spectrum. His combination of the spectroscope with photography to study the Solar System resulted in the discovery that the Sun's atmosphere contains hydrogen, among other elements (1862), and in 1868 he published his large map of the normal spectrum of the Sun in Recherches sur le specter solaire, including detailed measurements of more than 1,000 spectral lines, which for a long time remained a reference in terms of wavelength, even though his measurements were inaccurate by one part in 7,000 or 8,000 because the meter that he used as standard was too short.

Ångström was the first, in 1867, to examine the spectrum of the northern lights, and he detected and measured the characteristic bright line in the yellow-green region, although he was wrong to assume that this very line, sometimes known as his name would also be seen in the zodiacal light.

He died in Uppsala on June 21, 1874.

His son Knut Ångström was known for his work at Uppsala University on solar radiation, the radiation of heat from the Sun and its absorption by the Earth's atmosphere. For this research he developed several delicate methods and instruments, including his electrical compensation pyrometer, invented in 1893, and an apparatus for obtaining a photographic representation of the infrared spectrum in 1895.

Awards

Awards

• Rumford Medal in 1872.

Eponyms

• Angstrom unit was created in his honor (1 Å = 10^{- 10} m) used to measure the wavelength of light or interatomic distances in matter. This unit is also used in crystallography, as well as spectroscopy.
• On the Moon there is a crater named Ångström in his honor.
• The asteroid (42487) Angstrom bears this name in his memory.
• The Ångström Laboratory, one of the main buildings complexes of the University of Uppsala, bears its name in its honor.