Rockville Science Tuesday: Why the Greenwich Meridian Moved
Dr. P. Kenneth Seidelmann will discuss when, why, and how the Earth’s prime meridian moved.
In 1884, a delegation of international representatives convened in Washington, D.C. to recommend that Earth’s prime meridian (the north-south line marking zero degrees longitude) should pass through the Airy Transit Circle at the Royal Observatory in Greenwich, England. Modern navigators, mapmakers, surveyors, and London tourists now find that zero longitude runs 334 feet east of the telescope, according to GPS receivers. When, Why, and How did this happen? Largely because newer technologies, which use radio astronomy and satellites to precisely measure the rotation of the Earth and grid coordinates at any point on the Earth’s surface , replaced the traditional optical telescopic observations.The talk will describe the research, scientific paper publication, which has been downloaded over 17,000 times, and the press release, that received media coverage on five continents.
Dr. P. Kenneth Seidelmann was Director of Astrometry at the U.S. Naval Observatory. He was a leader in the international revisions of reference systems. He directed the modernizing of the almanacs and the introduction of electronic almanacs. He is a codiscoverer of the Saturn satellite Calypso. He calculated the analemma for the Longwood Gardens Sundial, and prepared the star charts for the Einstein Statues on the National Academy of Sciences grounds in Washington and Jerusalem. He was a member of the Wide Field/Planetary Camera Team of the Hubble Space Telescope. Dr. Seidelmann received an E.E., M.S. and Ph.D. degrees and a Distinguished Alumni Award from the University of Cincinnati. He is author of over one hundred scientific papers. He has taught courses in Celestial Mechanics at Catholic University of America and the University of Maryland. He is co-author of three books, “Fundamentals of Astrometry”, “TIME, From Earth Rotation to Atomic Physics” 1st and 2nd Editions, and “Celestial Mechanics and Astrodynamics: Theory and Practice”, and co-editor of the “Explanatory Supplement to the Astronomical Almanac”. Ken is past president of IAU Division I, the Celestial Mechanics Institute, and The Institute of Navigation (ION). He is a recipient of the ION Hays Award and the AAAS Award for International Scientific Cooperation. Minor planet 3217 is named “Seidelmann” in his honor.
The Rockville Science Tuesday lecture series meets on the second Tuesday of the month at the Rockville Senior Center. The program is free and open to everyone. About the Rockville Science Center Rockville Science Center Inc. is a 501(c)(3) organization with the goal of launching a vibrant science facility that will offer people of all ages and backgrounds the opportunity to explore the wonders of science and connect with the scientific community in our region.