Lockyer, Joseph

Astronomers use spectroscopy to identify the composition of the sun and other stars. A striking example is the discovery of the element helium. In 1868, astrono-mers viewing a solar eclipse observed emission lines that did not match any known element. The English astronomer Joseph Lockyer attributed these lines to a new element that he named helium, from hellos, the Greek word for the sun. For 25 years the only evidence for the existence of helium was these solar spectral lines. 

Helium - the atomic number is 2 and the chemical symbol is He. The name derives from the Greek helios for sun . The element was discovered by spectroscopy during a solar eclipse in the sun s chromosphere by the French astronomer Pierre-Jules-Cesar Janssen in 1868. It was independently discovered and named helium by the English astronomer Joseph Norman Lockyer. It was thought to be only a solar constituent until it was later found to be identical to the helium in the uranium ore cleveite by the Scottish chemist William Ramsay in 1895. Ramsay originally called his gas krypton, until it was identified as helium. The Swedish chemists Per Theodore Cleve and Nils Abraham Langet independently found helium in cleveite at about the same time. 

Sir Joseph Norman Lockyer, 1836-1920. Director of the solar physics observatory of The Royal College of Science at South Kensington. Pioneer in the spectroscopy of the sun and stars. In 1868 Lockyer and Janssen independently discovered a spectroscopic method of observing the solar prominences in daylight. Such observations had previously been made only at the time of total eclipses of the sun. 

But no one had ever subdivided a hydrogen atom, nor had they convincingly transmuted one element into another. So why credit this untested idea In the 1870s, the astronomer Joseph Norman Lockyer suspected that it was simply a question of finding the right conditions. Lockyer proposed that to transmute elements you needed the fiery furnace of a star. 

Joseph Lockyer (1836-1920) was one of the pioneers of solar spectroscopy. In examining the spectra of solar prominences in 1869, Lockyer noticed an absorption line that he could not identify. Reasoning that it represented an element not present on Earth, he proposed a new element - helium, from the Greek word helios for Sun. This idea failed to achieve acceptance from Lockyer s scientific colleagues until a gas having the same mysterious spectral line was found 25 years later in rocks. The helium in terrestrial uranium ore formed as a decay product of radioactive uranium. Thus, this abundant element was first discovered in the Sun, rather than in the laboratory. Lockyer s cosmochemical discovery was recognized by the British government, which created a solar physics laboratory for him. Lockyer also founded the scientific journal Nature, which he edited for 50 years. 

Pierre Janssen, studies the spectra of a solar eclipse and finds evidence of a new element. Edward Frankland, an English chemist, and Joseph Lockyer, an English astronomer, suggest the name helium. 

In 1868, a total solar ecHpse provided a unique oppoitunity to apply the spectroscope to stellar chemistry. At the moment when the Sun was perfectly eclipsed, the solar prominences surrounding the dark disk provided discrete line-emission spectra. Among these was a series of lines that matched no known elements. The discoverer, Joseph Norman Lockyer (1836-1920), postulated the existence of a new chemical element, helium after Helios (or Sun). The names of most metals typically end in ium or um and since most elements are metals hehum was first assumed to be a metal and named accordingly. Some 27 years later, helium was identified as a gas emanating from the uranium-containing mineral cleveite by William Ramsay. 

Spectroscopy was also used to look at the light from the Sun and stars. Scientists Joseph Lockyer and Pierre Janssen did this. In 1868, they looked at the Sun s spectrum during an eclipse. They found lines for an element they did not know. The new element was called helium. Later, scientists found helium on Earth, too. 

Soon afterwards Ramsay discovered a second new gas by heating the mineral cleveite. The spectrum of this gas showed a line coincident with a Fraunhofer line that been observed in the solar spectrum in 1868 by the astronomer Joseph Norman Lockyer (1866-1920) Since the line was not shown by any element known on earth, Frankland had named it helium after the Greek helios meaning sun. Ramsay found that his terrestrial helium was as unreactive as argon. 

He propounded the theory of valency and, with Joseph Lockyer, discovered helium in the Sun s atmosphere in 1868. 

A pioneer of thermochemistry, Julius Thomsen was first and foremost an experimentalist. Yet he also had an interest in chemical theories, and he was the only Danish scientist who, until Bohr in 1913, actively examined and contributed to the understanding of the periodic system. As mentioned, ever since the 1860s he entertained the heterodox view that the atoms of chemistry are complex particles and that this is revealed by regularities in their atomic weights. Of course, he was far from the only neo-Proutean of his time, but he was one of the most distinguished and articulate advocates of the idea of a basic unity of matter. In a work of 1887 he connected for the first time this idea with the periodic system, undoubtedly inspired by an address that William Crookes (1832-1919) had given the year before to the British Association for the Advancement of Science.Another likely inspiration was the British astronomer Joseph Norman Lockyer (1836-1920), whose work on the cosmic evolution of the elements had a great deal of similarity with the views expounded by Thomsen. 

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