Anders Jonas Ångström
Who was Anders Jonas Ångström?
Swedish physicist and astronomer who pioneered spectroscopy and gave his name to the angstrom unit of measurement for atomic-scale distances.
Biographical data adapted from Wikipedia’s article on Anders Jonas Ångström (CC BY-SA 4.0).
Biography
Anders Jonas Ångström was born on August 13, 1814, at Lögdö bruk, an ironworks estate in Sweden's Medelpad region. He studied at Uppsala University, where he spent almost his entire academic career, eventually becoming a professor of physics and later the keeper of the astronomical observatory. He married Augusta Carolina Bedoire, and Uppsala remained his home and professional base until he passed away on June 21, 1874, at the Uppsala Cathedral Assembly.
Ångström played a key role in the developing science of spectroscopy, the study of how matter interacts with light energy. In 1852, he published "Optiska undersökningar" or "Optical Investigations," formulating a law of absorption. It stated that a gas absorbs light of the same wavelengths it emits when it is incandescent. This principle was later refined by Gustav Kirchhoff and became known as Kirchhoff's law of thermal radiation, although Ångström's earlier work is well recorded.
One of Ångström's most notable achievements came in 1862 and 1868, with detailed maps of the solar spectrum. His 1868 atlas, "Recherches sur le spectre solaire," listed the wavelengths of about one thousand Fraunhofer lines in the solar spectrum with great accuracy. He used units of one ten-billionth of a meter for measuring these tiny wavelengths, a scale that turned out to be so useful for atomic and optical measurements that the scientific community named the unit after him. One angstrom, symbolized Å, equals 10 to the negative tenth power of a meter and is still widely used in crystallography, chemistry, and physics.
Ångström also made important contributions to the study of the aurora borealis. In 1867, he was the first to measure the spectrum of the northern lights, identifying a bright line in the green part of the spectrum. This line, later found to be from excited oxygen atoms in the upper atmosphere, was called the auroral line for many years. His work showed that the aurora was an electromagnetic phenomenon from the upper atmosphere rather than just an optical oddity.
In addition, Ångström researched terrestrial magnetism and heat transfer, showing the broad interests typical among nineteenth-century physicists. His scientific achievements led to his election as a Foreign Member of the Royal Society in 1870, and in 1872, he received the Rumford Medal from the Royal Society for his solar spectrum research. He died in Uppsala in June 1874 at the age of fifty-nine, leaving a significant impact on observational astronomy and optical physics.
Before Fame
Ångström grew up in Sweden when natural philosophy was making way for more rigorous experimental science in Europe. Lögdö bruk's ironworks setting, where his father was a clergyman, provided a humble yet intellectually aware environment. He attended Uppsala University, the oldest and most prestigious learning institution in Sweden, to study mathematics and physics at a time when the university was bolstering its scientific programs.
After finishing his studies, Ångström stayed at Uppsala as a teacher and researcher, gradually becoming an expert in optics and heat. Although Sweden in the mid-1800s wasn't the hub of European scientific activity, Uppsala kept in touch with the wider scientific community. Ångström corresponded with researchers across Europe, and his precise experimental work, especially in optical measurements, gained significant attention in the 1850s, establishing him as a leading figure in the new field of spectroscopy.
Key Achievements
- Produced the first comprehensive atlas of the solar spectrum in 1868, cataloguing approximately one thousand Fraunhofer absorption lines with high precision
- Gave his name to the angstrom unit of measurement, equal to one ten-billionth of a meter, now standard in atomic and molecular science
- Recorded the first spectroscopic measurement of the aurora borealis in 1867, identifying its characteristic green emission line
- Formulated an early version of the absorption law later generalized as Kirchhoff's law of thermal radiation, published in 1852
- Received the Rumford Medal from the Royal Society in 1872 and was elected a Foreign Member of the Royal Society in 1870
Did You Know?
- 01.Ångström was the first scientist to successfully measure the spectrum of the aurora borealis, accomplishing this in 1867 and identifying what became known as the auroral green line, later explained as emission from excited oxygen atoms.
- 02.His 1868 solar spectrum atlas was so precisely constructed that the unit of wavelength measurement he used, one ten-billionth of a meter, was posthumously named the angstrom in his honor and is still used today in X-ray crystallography and nanotechnology.
- 03.His son Knut Ångström also became a notable physicist, specializing in solar radiation and atmospheric absorption, making the Ångströms one of the few father-and-son pairs each to leave a distinct mark on physical science.
- 04.Ångström articulated a precursor to Kirchhoff's law of thermal radiation in 1852, several years before Kirchhoff's more famous formulation, though historical credit has predominantly attached itself to Kirchhoff.
- 05.Despite producing one of the most precise measurements of solar spectral lines in nineteenth-century science, Ångström worked primarily at Uppsala, far from the major observatories of Paris, London, or Berlin.
Family & Personal Life
Awards & Honors
| Award | Year | Details |
|---|---|---|
| Rumford Medal | 1872 | — |
| Foreign Member of the Royal Society | 1870 | — |