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THE ASTRONOMICAL SOCIETY
OF THE PACIFIC

112th ANNUAL MEETING

HISTORY SESSIONS
Presented by the ASP History Committee
Saturday, 15 July 2000, Pasadena, CA

INVITED LECTURES

3:00 THREE NINETEENTH CENTURY PROFESSIONAL ASTRONOMERS’ VIEWS ON LIFE BEYOND EARTH
Donald E. Osterbrock, Lick Observatory, University of California, Santa Cruz
    People here on Earth have long been interested in the possibility of life on other worlds in the sky. Astronomers, whatever their fields of expertise, have often been consulted, or offered themselves as consultants on this question. Three American main-line astronomers, reaching back 150 years and more into the past, who wrote and spoke extensively to the public on this subject were Ormsby MacKnight Mitchel (1809-1862), Charles A. Young (1834-1908), and Simon Newcomb (1835-1909). Mitchel, a fantastically successful lecturer, could be considered in many ways America’s first Carl Sagan. He traveled around the country, drawing huge crowds who paid to hear him lecture on the wonders of the universe, as he raised money to support the Cincinnati Observatory. It was owned by its stockholders, a society he had founded, and whose members he had personally recruited. Young, a pioneer solar physicist and astrophysicist, and Newcomb, an orbital expert, are better known today; they both were outstanding scientists. All three lectured extensively and published many articles and books. Their specific ideas on life on other planets will be discussed and compared; all three worked in terms of the knowledge, theories, and beliefs of their times, just as we do today.

3:25 STARLIGHT AND STARLETS: HARVARD’S FAIR COMPUTERS IN THE 1890S
Barbara L. Welther, Smithsonian Astrophysical Observatory
    This paper will examine the early years of the Draper Memorial program at Harvard College Observatory and the role that women played in it. In the 1890s Williamina Fleming set up the initial Harvard System of classifying stellar spectra and Antonia Maury developed an independent two-dimensional system based on enhanced photographs of bright stars in the northern hemisphere. To please his patron, Mrs. Draper, Edward Pickering, the Director of HCO, had Mrs. Fleming and a team of women assistants prepared for publication a small catalogue of spectral types for 10,000 stars. The assistants became known as the “Corps of Women Computers.” Much of their work was to precess star positions from 1875 to 1900 for the new Draper Memorial. They also had to perform many other clerical tasks. One task was to prepare card catalogues of the stars under investigation. In the German catalogues the stars were arranged by declination. For the new Draper catalogue they were to be ordered by right ascension—truly a job for computers! Some of the women like Williamina Fleming and Annie Jump Cannon became famous for their work, especially for their discoveries of novae and variable stars. They were featured in numerous newspaper and magazine articles. Although many of the other women didn’t receive that kind of individual recognition, they still received aggregate acclaim as a member of the team. They performed the myriad tasks necessary to prepare and format the stellar data for publication. At that time, it was very unusual for women to participate in a scientific endeavor. Proud of their role, they saved the many pictures and newspaper clippings written about them for us to examine a century later.

3:50 “I AM ALMOST CERTAIN...”: WILLIAM HUGGINS AND THE FIRST ATTEMPTS TO MEASURE STELLAR MOTION IN THE LINE OF SIGHT
Barbara Becker, WestEd and University of California, Irvine
    When, in 1841, Christian Doppler proposed his now-familiar principle that the pitch heard emanating from a moving sound source depends on that source’s velocity relative to the listener, he suggested that the principle should also apply to light emitted by stars. In fact, he hypothesized that the color of stars might be attributed to their motion along the line of sight. His prediction concerning sound was confirmed a few years later, but there was then no comparable way to put his claims about starlight to the test. This changed with the introduction of the spectroscope into the astronomer’s toolkit in the 1860s. In February 1868, William Huggins (1824-1910)—an amateur astronomer and pioneer in the emerging field of astrophysics—became the first to apply Doppler’s principle to the light of a star. It was an effort fraught with overwhelming mensurational and interpretive difficulties. Huggins’ observatory notebook records bring new evidence to bear on both the steps he took to overcome these challenges and the rhetorical means by which he persuaded his contemporaries that he had, in fact, accomplished what he claimed. The paper presents an historical analysis of these unpublished materials and of Huggins’ role in the introduction of this new method into astronomical research.

4:15 “HE STILL BLUSHES WHEN HE THINKS ABOUT IT”: HENRY NORRIS RUSSELL’S ENCOUNTER WITH EROS
David DeVorkin, National Air and Space Museum, Smithsonian Institution
    Soon after its discovery on 13 August 1898 and its provisional designation DQ, as the 433rd minor planet discovered, astronomers realized that Eros’ mean distance from the Sun was less than that of Mars, and its highly eccentric orbit brought it very close to Earth. This meant that the minor planet could be used to triangulate the distance between Earth and the Sun, the solar parallax. Russell became one of many who studied the planetary passage at the turn of the century. He did not observe it himself, but made it possible for others to observe it by computing its ephemeris and then predicting how its orbit would be perturbed by Mars. This study became his PhD thesis at Princeton and stands as an example of what constituted acceptable normative practice in astronomy at the turn of the Century. It will also serve to demonstrate how the tools of astronomy have changed in the intervening century, capped by the space probe NEAR, which appropriately went into a parking orbit about Eros on Valentine’s day, 2000. Henry probably would have blushed.

4:40 THE BEAUTIFUL EARLY TELESCOPES OF WARNER AND SWASEY, INCLUDING THE J.A. BRASHEAR AND C.S. HASTINGS OPTICAL COLLABORATION
John W. Briggs, Yerkes Observatory, University of Chicago
    From the first in 1880, Warner & Swasey telescopes were as handsome as they were practical. The earliest was sold to Beloit College and carried a 9 1/2-inch lens made by Alvan Clark & Sons. The second, also a 9 1/2-inch, went to Hartford High School, and its refined design was a stepping-stone to later, more standard models. An old Warner & Swasey at Johns Hopkins University, long in storage but recently restored for display, has been recognized as a twin to the elegant Hartford refractor—the only difference being that its unusual 9.4-inch objective was designed and figured by C. S. Hastings rather than by the Clarks. The Hartford and Johns Hopkins instruments are thus both of a very early form. In certain interesting design details, they may be unique among surviving Warner & Swasey telescopes. Slides will dramatize the sculpted beauty and masterful machining evident in these and other early Warner & Swasey products.

5:05 MODERN COMETARY MODELS USING ANCIENT CHINESE OBSERVATIONS
Donald K. Yeomans, Jet Propulsion Laboratory
    For more than two millennia, ancient Chinese court astronomers maintained a rather comprehensive record of cometary sightings. Owing to the significance of comets as portents for the reigning emperor, early sky watchers from China (as well as their counterparts from Korea and Japan) carefully noted each cometary apparition for the purpose of astrological predictions. When possible, the dates and corresponding celestial locations and motions were recorded and in some cases, the colors, coma sizes, and tail lengths were also noted. These ancient Chinese observations represent the only source of information available for modeling the long-term behavior of periodic comets. For comets Halley and Swift-Tuttle, Chinese records have been identified as far back as 240 B.C. and 69 B.C. respectively and these data have been used to define their long-term motions. As a result, cometary heliocentric and geocentric distances for each Chinese sighting of these two comets can be computed and estimates can be made for each comet’s intrinsic brightness at various observed returns. For both comets Halley and Swift-Tuttle, their absolute magnitudes, and hence their outgassing rates, have remained relatively constant for two millennia. For comet Halley, this outgassing takes place preferentially after perihelion when localized active regions are exposed to sunlight. This outgassing pattern, which consistently delays the comet’s return by 4 days per period, requires that the spin state of Halley’s nucleus be relatively stable over many orbital revolutions. For the nucleus of comet Swift-Tuttle, we conclude that its mass is at least an order of magnitude larger than comet Halley because, while its outgassing rate is comparable to Halley’s nucleus, its motion is unaffected by rocket-like outgassing accelerations. Although the earliest identified apparition of comet Tempel-Tuttle is A.D. 1366, the associated Leonid meteor showers were noted back to at least A.D. 902. The Leonid meteor stream is young in the sense that outstanding meteor displays occur only near the time of the parent comet’s perihelion passages. The ancient Chinese records of the Leonid meteor showers and storms have been used to map the particle distribution around the parent comet and this information was used to guide predictions for the 1998-1999 Leonid meteor showers.

 

Presented by the ASP History Committee
Katherine Bracher, Whitman College (chair)
John W. Briggs, University of Chicago
Roy H. Garstang, University of Colorado
Richard A. Jarrell, York University
E.C. Krupp, Griffith Observatory
Donald E. Osterbrock, University of California, Santa Cruz
Joseph S. Tenn, Sonoma State University
Barbara L. Welther, Smithsonian Astrophysical Observatory
Thomas R. Williams, Rice University

JST
2000-04-19