115
See also: Observing Uranus 84–85 ■ Messier objects 87 ■
The sun’s spectrum 112
THE RISE OF ASTROPHYSICS
nebulae are indeed composed of
stars, and are galaxies in their own
right. The second type of nebula he
observed was entirely different. Its
light spectrum was made of single-
wavelength emission lines—energy
was being emitted as one color;
there were no absorption lines.
Huggins realized that these
second kind of nebula were huge
clouds of hot, low-density gas.
Some of this gas could be in the
process of forming new stars;
other gas clouds, like the planetary
nebulae, could have been ejected
from evolving stars.
Huggins’ 1864 observations
of the Cat’s Eye planetary nebula in
the constellation Draco revealed a
spectrum with a single absorption
line, produced by hot hydrogen gas.
However, the nebula also emitted
Huggins was the first to analyze
the spectrum of a planetary nebula (the
Cat’s Eye nebula), confirming that it
was gaseous and not composed of stars.William Huggins
After selling the family
drapery business when he
was 30, William Huggins
ran a private observatory in
Tulse Hill in South London.
He used his new wealth
to buy a powerful 8-in
(20-cm) refracting telescope.
In 1875, age 51, Huggins
married 27-year-old Irish
astronomy enthusiast
Margaret Lindsey, who
encouraged him to adopt
photography to record his
spectra and was an active
partner in his later research,
co-authoring many papers.
Huggins was a pioneer in the
use of photography to record
astronomical objects. He
also developed a technique
to study the radial velocity
of stars using the Doppler
shift of their spectral lines.
As a pioneer astronomical
spectroscopist, Huggins was
elected to serve as president
of the Royal Society from 1900
to 1905. He died at his home
in Tulse Hill in 1910, age 86.Key works1870 Spectrum analysis
in its application to the
heavenly bodies
1909 Scientific Papersenergy in two strong green lines,
which did not correspond to any
known chemical element. Some
astronomers suggested that they
were produced by a new element,
dubbed nebulium.
Huggins concluded from his
spectroscopic observations that
all of the heavenly bodies he had
studied were made of exactly the
same elements as Earth. However,
the mystery of nebulium was
not solved until after his death.
In 1927, it was found to be simply
doubly ionized oxygen—oxygen
atoms that have lost electrons and
have a double positive charge. ■