Ångström, Anders Jonas

Ångström, Anders Jonas

(born Aug. 13, 1814, Lögdö, Swed.—died June 21, 1874, Uppsala) Swedish physicist. From 1839 he taught at the University of Uppsala. He devised a method of measuring thermal conductivity, showing it to be proportional to electrical conductivity, and deduced that an incandescent gas emits rays of the same refrangibility as those it can absorb. A founder of spectroscopy, he discovered that hydrogen is present in the Sun's atmosphere, published a map of the normal solar spectrum, and was the first to examine the spectrum of the aurora borealis and to detect and measure the characteristic bright line in its yellow-green region. The angstrom (10⁻¹⁰ m), a unit of length, was named in his honour.