  When V. M. Slipher gave the 1933 George Darwin lecture to the Royal
Astronomical Society, it was natural that he spoke on spectrographic studies of
planets. Less than one-sixth of his published work deals with globular clusters
and the objects we now call galaxies. In his most productive years, when he had
Percival Lowell to give him direction, Slipher made major discoveries regarding
stars, galactic nebulae, and solar system objects. These included the first
spectroscopic measurement of the rotation period of Uranus, evidence that
Venus's rotation is very slow, the existence of reflection nebulae and hence
interstellar dust, and the stationary lines that prove the existence of
interstellar calcium and sodium. After Lowell's death in 1916 Slipher continued
making spectroscopic observations of planets, comets, and the aurora and night
sky. He directed the Lowell Observatory from 1916 to 1954, where his greatest
achievements were keeping the observatory running despite very limited staff
and budget, and initiating and supervising the "successful" search for Lowell's
Planet X. However, he did little science in his last decades, spending most of
his time and energy on business endeavors.
