William Huggins was a leading pioneer in the
use of spectroscopy in the 19th century. He set up an eight inch
refractor telescope in his home in 1858.
He was an amateur with no university training, but eventually was knighted for his service to science. Huggins eventually became the President of the Royal Society (1900-1905). In 1875 he married Margaret Lindsay Murray of Dublin. She became a significant partner in his spectroscopic studies and co-authored several publications with him.
He quickly saw the significance of
analysis of the sun (1859) based on spectral analysis and started to apply
this to stellar spectra.
By 1863 he was able to publish lists of stellar spectral lines. He refers to the period immediately after 1858 in essay:
" I soon became a little dissatisfied with the routine
character of ordinary astronomical work, and in a vague way sought about
in my mind for the possibility of research upon the heavens in a new direction
or by new methods. It was just at this time ... that the news reached me
of Kirchhoff's great discovery of the true nature of the chemical composition
of the sun from his interpretation of the Fraunhofer
lines. Here at last presented itself the very order of work for which in
an indefinite way I was looking - namely, to extend his novel methods
of research upon the sun to the other heavenly bodies."
( "The New Astronomy: A Personal Retrospect," in The Nineteenth Century, 41(1897),911 )
The chemical analysis of the sun was considerably easier than that of starlight which is much reduced in intensity. We see in Huggin's work a significant connection between terrestrial chemistry and celestial chemistry. Now , in the field of chemistry, the vast distances between earth and the cosmos were breached by the field of spectroscopy. What Newtonian mechanics had done in uniting the motions of bodies on earth with those in the solar system, spectroscopy now did on a far grander scale, embracing all of the observable universe. In Huggin's own words:
" Then it was that an astronomical observatory began,
for the first time, to take on the appearance of a laboratory. Primary
batteries, giving forth noxious gases, were arranged outside one of the
windows; a large induction coil stood mounted on a stand on wheels so as
to follow the positions of the eye-end of the telescope, together with
a battery of several Leyden jars; shelves with Bunsen burners, vacuum tubes,
and bottles of chemicals ... lined its walls.
The observatory became a meeting place where terrestrial chemistry was brought into direct touch with celestial chemistry. ...
... almost every night's work was red-lettered by some discovery."
( "The New Astronomy: A Personal Retrospect," in The Nineteenth Century, 41(1897),913 )
In the middle of the 19th century there was still debate about the nature of the nebulae. Were they clouds of diffuse matter or were they very distant collection of stars whose great distance made it impossible to resolve the individual stars? Huggins, on August 29, 1864 investigated the planetary nebula in Draco and was startled to find that the spectrum was dominated by a single green line with a two satellite lines towards the blue. This spectrum was entirely different from any stellar spectrum he had observed before. The conclusion was inescapable that the nebula was not a mass of unresolved stars, but a brightly glowing gas. Moreover, we see in his memoirs a striking departure from the view that the celestial bodies are eternal and unchanging;
"Further observations soon convinced me that, though
the short span of human life is far too minute relatively to the cosmic
events for us to expect to see in succession any distinct steps in so august
a process, the probability is indeed overwhelming
in favor of an evolution in the past, and still going on, of the heavenly
Hubble image of Draco nebula
The Scientific Papers of Sir William Huggins, ed. by Sir William Huggins and Lady Huggins(London: William Wesley and Son, 1909), pp. 105-8.
Huggins also developed the idea of using the Doppler shift as a means to determine celestial motion along the sight of the observer. Although, in principle, one could measure the velocity transverse to the line of sight, in fact, the stars are so far away that it is a heroic effort to see such motion. One could say that without the use of the Doppler effect it would be impossible to ascertain anything about stellar motion. In 1868 Huggins announced the first successful application of the Doppler effect in a paper printed in the Transactions of the Royal Society. He explains why it took so long for Doppler's suggesion to be put to practical use.
" ...no attempts had been made, nor were indeed possible,
to discover by this principle the motions of the heavenly bodies in the
line of sight. For, to learn whether any change in the light had taken
place from motion in the line of sight, it was clearly necessary to know
the original wave length of the light before it left the star.
A soon as our observations had shown that certain earthly substances were present in the stars, the original wave lengths of their lines became known, and any small want of coincidence of the stellar lines with the same lines produced upon the earth might safely be interpreted as revealing the velocity of approach or recession between the star and earth.
"... From the beginning of our work upon the spectra of the stars, I saw in vision the application of the new knowledge to the creation of a great method of astronomical observation which could not fail in the future to have a powerful influence on the progress of astronomy; ..."
Huggins had tried to photograph the spectrum of Sirius
as early as 1863 but got poor results. From about 1875 onward Huggins began
to get better results and developed better photographic techniques. By
1879 he was able to photograph ultra-violet spectra. Along
with other astronomers he was able to show that white stars were abundant
in hydrogen. This was important in that it began to reveal the great abundance
of hydrogen in the universe.
The Scientific Papers of Sir William Huggins, ed. by Sir William Huggins and Lady Huggins(London: William Wesley and Son, 1909), pp. 195-197
Modern Theories of the Universe: from Herschel to Hubble, Michael J. Crowe,
Dover Publications, New York, 1994
The Norton History of Astronomy and Cosmology, John North, W. W. Norton & Co., Inc., New York, 1995