Presented by the ASP History Committee

History I: The Lowell Observatory in 20th Century Astronomy
Tuesday, 28 June 1994, Northern Arizona University, Flagstaff, AZ


8:45 The Lowell Observatory: a Trustee’s View
    Lowell Observatory differs from most other public foundations in that its Board of Trustees consists of only one person. To date four relatives of the founder have served in that role. I will describe some of the trials (literally) and tribulations of my predecessors and myself in bringing my great-uncle Percy’s observatory from the nineteenth century to the eve of the twenty-first.

9:15 Percival Lowell, W.H. Pickering and the Founding of the Lowell Observatory
DAVID STRAUSS, Kalamazoo College
    The founding of the Lowell Observatory has been neglected by historians in favor of Lowell’s Martian research. Important in its own right, the founding must be understood in the scientific and cultural context of the 1890s. The cultural institutions of Boston, especially Harvard College, facilitated the collaboration between Lowell and W.H. Pickering which was necessary to launch the new observatory. While Lowell turned to Harvard and the Pickering brothers for expertise, he also struggled to protect his observatory’s autonomy against the imperial ambitions of the larger institution. Without Lowell’s determination, the Lowell Observatory might very well have become, like Arequipa, another station in the Harvard network.

10:05 Different Perceptions: Lowell and Barnard’s Views of Mars in 1894
    Public interest in the planet Mars soared during the two decades following Schiaparelli’s discovery of canals in 1877, and it reached a peak in the 1890s. Observatories were built expressly for the purpose of studying the planet, including that of Percival Lowell at Flagstaff. During the critical year 1894, Mars came to the last really good opposition of the century. Lowell’s observations are contrasted with the very different results obtained by the noted astronomer E.E. Barnard at the Lick Observatory. What they saw was determined not only by atmospheric conditions and optics; it was also significantly colored by the medium of their interests and personalities.

10:35 Edwin Hubble, Vesto Melvin Slipher, and the Classification of Nebulae
ROBERT W. SMITH, Smithsonian Institution [Read by RONALD BRASHEAR, Huntington Library.]
    V.M. Slipher (1875-1969) was one of the leading observational astrophysicists of his generation, with a string of important findings to his name. In this talk, I shall focus on those observations that had the most import for cosmology, particularly his momentous discovery of the very high redshifts of spiral nebulae, a discovery that would prove crucial to the development of ideas of the expanding universe.

11:05 From Planet X to Pluto: Predictions, Searches, Discovery, Calculations
DONALD E. OSTERBROCK, Lick Observatory, University of California, Santa Cruz
    Soon after the discovery of Neptune in 1846, astronomers began speculating about, searching for, and predicting a ninth planet. The most serious and determined seekers were William H. Pickering and Percival Lowell. The latter’s first known prediction of it was made in 1902, his first search began in 1905, and his first calculations to determine its position began that same year. His basic idea of its orbit was correct, but his idea of its mass was wrong. He returned to this problem, theoretically and observation- ally, several times. After Lowell’s death in 1916, his hand-picked successor, V. M. Slipher, worked for the instrument which the previous attempts proved would be necessary for success. Trustees Guy Lowell and Roger Putnam, and Lowell’s brother, A. Lawrence Lowell, all made important contributions to the project. Slipher found Clyde Tombaugh, the ideal person to carry out the search, and Tombaugh found Pluto in 1930. The Lowell astronomers could not calculate its orbit accurately themselves, but others quickly did so. Pre-discovery positions, including some obtained from plates taken in earlier, unsuccessful searches, helped improve the orbit. Ernest W. Brown almost immediately concluded that the prediction was not a true one, but resulted largely from errors in the earliest pre-discovery positions of Uranus. Eleven years later Vladimir Kourganoff disputed this, but we know now (from Pluto’s measured mass) that Brown was right. Nevertheless Percival Lowell deserves a major share of the credit for the discovery, because his dedication to this problem convinced Slipher, Tombaugh, and the others that Planet X would be there and that Lowell Observatory could discover it.

11:35 John Scoville Hall, the Fourth Director of Lowell Observatory
ROBERT L. MILLIS, Lowell Observatory


History II: Historic and Prehistoric Astronomy
Tuesday, 28 June 1994, Northern Arizona University, Flagstaff, AZ


1:30 Photoelectric Photometry: The First Fifty Years
JOHN B. HEARNSHAW, University of Canterbury
    This paper will review the development of photoelectric photometry during the half century prior to the introduction of the photomultiplier, when simple diode photocells were employed. The first electrical detection of starlight was made by William Monck in Dublin in 1892, using a photovoltaic cell constructed by George Minchin. Joel Stebbins in Illinois used a selenium photoconductive cell starting in 1907. However, the photoelectric potassium hydride cells made by Julius Elster and Hans Geitel in Germany, and shortly afterwards by Jakob Kunz in Illinois, marked the beginning of stellar photoelectric photometry in 1912. The principal early pioneers were Paul Guthnick and Richard Prager in Berlin, followed by Joel Stebbins and his colleagues in Illinois, later Wisconsin. These observers developed the practice of photoelectric photometry into a highly skilled technique which produced useful scientific results. Between 1912 and 1940 many others tried to emulate the successes of the Berlin and Illinois (or Wisconsin) observers. At least 38 observers at 22 different observatories attempted photoelectric photometry, but with varying degrees of success. Those who had the direct assistance of physicists, who in turn understood the practical problems of electronic devices, were the most successful. In the period prior to 1940 several major improvements in instrumentation were devised. These included the Lindemann electrometer (1924), thermionic d.c. amplification of the anode currents (Rosenberg 1920, Whitford 1932) and the introduction of the cesium-oxide on silver red-sensitive photocell into photometry by John Hall in 1931. Hall also pioneered the use of cooled photocells to reduce the dark emission. In 1937 V.B.Nikonov in Russia built a photometer with a Fabry lens to give stable cathode illumination. Nevertheless, photoelectric photometry was throughout this period the preserve of a few highly skilled observers. Some useful science was accomplished, along with many disappointments. Not until the first commercial photomultiplier tubes became available did photometry become less of an art and more of a routine technique.


2:20 Bengt Edlén (1906-1993): Spectroscopist
ROY H. GARSTANG, University of Colorado
    Edlén is especially remembered by astronomers for his identification of the spectral lines in the solar corona as arising from forbidden transitions in highly ionized ions of iron and nickel. He made many other spectroscopic studies. We review his life and his work on wavelengths and energy levels in ions of the light elements from lithium to fluorine, his measurements on various ions, such as Fe III and Fe IV, and his studies of isoelectronic sequences. We also recall his work on the refractive index of air, which improved the acuracy of vacuum-air wavelength conversions.

2:40 The Lowell Observatory-Indiana University Connection
FRANK K. EDMONDSON, Indiana University
    Daniel Kirkwood, Thomas Jefferson Jackson See, Joseph Swain, John A. Miller, and Wilbur A. Cogshall all played a part in the train of events that took V.M. Slipher to the Lowell Observatory in 1902, followed by C.O. Lampland in 1903. Their performance led Percival Lowell to establish the Lawrence Fellowship, named in memory of his mother, in 1905. It was available only to graduates of Indiana University, and those who held it were: J.C. Duncan (1905-06), E.C. Slipher (1906-07), K.P. Williams (four months in 1907), F.K. Edmondson (1933-34), and Lewis Larmore (1938-39). Albert G. Wilson abolished the Lawrence Fellowship for fiscal reasons shortly after he succeeded V.M. Slipher as Director. V.M. Slipher added the job of taking post-Pluto search plates to Edmondson’s Fellowship responsibilities shortly after he arrived. This job continued after the Fellowship year ended, and its unexpected consequences will be described.

2:55 The Babylonian Sky
SALLIE TEAMES, Stripling Middle School, Ft. Worth, TX
    Where did the Greeks get their constellations and most of their gods? from the Babylonians. Our knowledge of Babylonian astronomy comes directly from deciphered cuneiform tablets now stored in the British Museum. These tablets, discovered in the excavations of King Assur-banipal’s library at Ninevah, provide knowledge of Babylonian astronomy and its relationship to their gods.

3:10 Astronomical Symbolism on Old Coins
CARLSON R. CHAMBLISS, Kutztown University
    Many coins, both ancient and modern, depict astronomical themes. Among these are a special minting of gold coins of the Byzantine Emperor Constantine IX (reigned 1042-55) which may have been commemorative of the supernova of 1054. Under Augustus (Roman emperor from 27 BC to 14 AD) there was an issue of silver denarii depicting the comet which appeared in the sky shortly after the assassination of Julius Caesar in 44 B.C. In more recent times there have been coins depicting signs of the zodiac or honoring various astronomers and physicists.

History III: The Solar System in 20th Century Astronomy
Thursday, 30 June 1994, Northern Arizona University, Flagstaff, AZ


10:30 The History of Planetary Radar Astronomy
NICHOLAS RENZETTI and A.J. BUTRICA, Jet Propulsion Laboratory
    This paper will review the origins of radar technology in the 1920s and 1930s. The investigations of meteors and ionospheres led to the origins of radar astronomy in the 1930s and ’40s. This, in turn, led to planetary radar astronomy starting in the ’50s. We will describe the early radar astronomy observations in the U.S., Europe, and the USSR and early observations of the moon. It wasn’t until the late ’50s that serious attempts were made to get radar echo from Venus (achieved in March 1961). This led to planetary radar astronomy becoming a full, ongoing scientific activity contributing to our knowledge of the planets and their satellites, asteroids, and comets in our solar system. The initial observations of the Venus echo yielded considerable improvement in the value of the astronomical unit and the retrograde motion of the planet. The many international observations of Venus were followed by those of Mars, Mercury, the Galilean satellites, the rings of Saturn, and, recently, Saturn’s satellite Titan. We will discuss the intensive interaction between radio and radar astronomy from the 1950s to the present. As the space program evolved, opportunities for including radar instrumentation on the spacecraft became available and radar was implemented on the Pioneer Venus and Magellan missions. The paper will conclude with a description of the great Earth-based radar observatories currently operating in the U.S. and the Commonwealth of Independent States.

11:00 The Moon and Voyager: Highlights of Solar System Exploration
EUGENE M. SHOEMAKER, U.S. Geological Survey
    The earliest missions have often provided some of the most interesting discoveries and surprises in the exploration of the solar system by spacecraft. Ranger VII, VIII, and IX, flown to the Moon in 1964 and 1965, provided our first close-up view of the lunar surface. Surface resolution was increased by a factor of 1,000 over that previously attained with Earth-based telescopes. The small-crater size-frequency distribution was discovered, and craters generally smaller than 100 to 200 meters diameter exhibited a complete range of shape from fresh craters to those almost completely obliterated by subsequent bombardment. From these observations, the steady-state crater distribution was recognized, and it was possible to formulate the initial theory of the lunar regolith formed by small-body bombardment. Even some of the largest fragments in the regolith were recognized in Ranger VIII and IX images. Subsequent observations by the Surveyor lunar landers increased the resolution by another factor of 1,000 and provided direct observations on the fragmental constituents of the regolith, permitting a fairly complete theory to be derived. The Voyager spacecraft provided our first detailed observations of the satellites of the outer planets, converting these bodies from barely more than points of light seen at the telescope to known worlds with decipherable geology. Indeed, a host of inner satellites was discovered close to each of the major planets. The discoveries of active eruptive plumes on Io and Triton were total surprises. Perhaps equally exciting was the discovery of intricate unsuspected details in the ring systems of each planet, including the discovery of the Jovian ring system. Many of these details still defy theoretical understanding.

11:30 Comets and Applied Historical Astronomy
DONALD K. YEOMANS, Jet Propulsion Laboratory, Caltech
    For at least three periodic comets, ancient Chinese observations can be used to help develop modern cometary models. The ancient Chinese astrologers were capable of providing surprisingly accurate positional data for comets. Chinese observations of comets Halley and Swift-Tuttle span over two millennia and these data can provide stringent constraints upon modern cometary models. The spin axis of comet Halley’s nucleus and the active surface vents would appear to be remarkably stable over two millennia and the nucleus of comet Swift-Tuttle is likely to be far more massive than the nucleus of comet Halley. Although Chinese observations of comet Tempel-Tuttle extend back only to A.D. 1366, the Chinese recorded the debris train of this comet as Leonid meteor shower events back to the early tenth century. These meteor shower data can be used to map the likely particle distribution surrounding this comet and to help in making meteor shower/storm predictions for a few years on either side of the comet’s approaching return to perihelion in 1998.


Presented by the ASP History Committee
Horace W. Babcock, Observatories of the Carnegie Institution of Washington
Katherine Bracher, Whitman College
Donald E. Osterbrock, University of California, Santa Cruz
Woodruff T. Sullivan, III, University of Washington
Joseph S. Tenn, Sonoma State University (chair)
Craig B. Waff
Richard L. Walker, U.S. Naval Observatory, Flagstaff
Thomas R. Williams, Rice University
Donald K. Yeomans, Jet Propulsion Lab