Relating Time to the Earth's Variable Rotation


Book Description

With the beginning of the 21st Century, the timing community finds itself again facing a decades-old problem of how to synchronize a uniform time scale with time derived from the Earth's rotation. Atomic time is the basis for most everyday timing applications, However, time astronomically determined from the Earth's rotation is essential for other applications including navigation. The history of relating atomic time to the Earth's rotation is presented, including background information related to the current synchronization method of leap seconds.




The Earth's Variable Rotation


Book Description

An analysis of the irregular rotation of the Earth and the geophysical mechanisms responsible for it.




Time: From Earth Rotation to Atomic Physics


Book Description

This accessible reference presents the evolution of concepts of time and methods of time keeping, for historians, scientists, engineers, and educators. The second edition has been updated throughout to describe twentieth- and twenty-first-century advances, progress in devices, time and cosmology, the redefinition of SI units, and the future of UTC.




Time


Book Description

Filling the need for a book that conveys the current technology as well as the underlying history and physical background, this book tells physicists and engineers how to measure time to the precision required for modern-day use. The authors draw on their longstanding research experience with timekeeping and high-precision measurement to cover the use of satellites in measuring earth movement variation and the influence of the moon, while also dwelling on such topics as timekeeping aboard satellites and time transfer. Indispensable for high-precision measurements of processes in astrophysics, and relevant for measurement, navigation and communication, this monograph can be equally used as a course book or as accompanying work at advanced undergraduate or graduate level.




Time, Globalization and Human Experience


Book Description

This edited volume focuses on the intersection of time and globalization, as manifested across a variety of economic, political, cultural, and environmental contexts. Since David Harvey’s influential characterization of globalization as "time-space compression", ample research has looked at the spatial aspect of the phenomenon, yet few have focused on globalization’s temporal aspects. Meanwhile, other publications have analysed problems of speed, acceleration, and the commodification of time, but while it often serves as the implicit or explicit backdrop for these studies of time, globalization is not investigated as a problem or a question in its own right. In response, this volume develops these conversations to consider how time shapes globalization, and how globalization affects our experience of time. The interplay between varying aspects of the human experiences of time and globalization requires the type of interdisciplinary approach that this volume takes. The contributors advance an understanding of global time(s) as an arena of contestation, with social, political, ecological, and cultural implications for human and other lives. In considering the diverse valences of time and globalization, they illuminate problems as well as possibilities. Topics covered include emerging infectious diseases, temporal sovereignty, worker exploitation and resistance, chronobiology, energy politics, activism and hope, and literary and cinematic representations of counter-temporalities, offering a rich and varied account of global times. This volume will be of great interest to students and researchers from a range of disciplines, including anthropology, cultural studies, globalization, international relations, literary studies, political science, social theory, and sociology.







Historical Eclipses and Earth's Rotation


Book Description

This book is intended for geophysicists, astronomers (especially those with an interest in history), historians and orientalists. The culmination of many years of research, it discusses, in depth, ancient and medieval eclipse observations and their importance in studying Earth's past rotation. This was the first major book on this subject to appear in the last twenty years. The author has specialised in the interpretation of early astronomical records and their application to problems in modern astronomy for many years. The book contains an in-depth discussion of numerous eclipse records from Babylon, China, Europe and the Arab lands. Translations of almost every record studied are given. It is shown that although tides play a dominant long-term role in producing variations in Earth's rate of rotation - causing a gradual increase in the length of the day - there are significant, and variable non-tidal changes in opposition to the main trend.




Proceedings of the Twenty Seventh General Assembly Rio de Janeiro 2009


Book Description

A complete record of the formal organisational and administrative proceedings of the XXVII General Assembly of the International Astronomical Union.




Variations in Earth Rotation


Book Description

Published by the American Geophysical Union as part of the Geophysical Monograph Series, Volume 59. As part of the Nineteenth General Assembly of The International Union of Geodesy and Geophysics Symposium (IUGG) in Vancouver, Canada, Union Symposium U4, "Variations in Earth Rotation" was held August 18-19 1987. The Convenor was Dennis D. McCarthy, U.S. Naval Observatory with P. Paquet, Observatoire Royal de Belgique and M. G. Rochester, St. Johns University serving as co-convernors. In a session on internal structure of the Earth papers dealt with the geophysical effects on Earth rotation parameters. Mantle anelasticity increases the free core nutation (FCN) period by a few days. The period of the FCN and the amplitudes of the main nutation components are sensitive to the ellipticity of the core?]mantle boundary (CMB), and a non-hydrostatic increase of 400m in the flattening of the CMB is a possible explanation of the discrepancies from theory. An alternative suggestion rests on the subseismic description of the nutation spectrum of the stratified liquid core. Evidently new models will have to take into account contributions from the oceans, mantle anelasticity, non-hydrostatic pre-stress, CMB topography and internal core structure.




Time and the Earth’s Rotation


Book Description

IAU Symposium No. 82, "Time and the Earth's Rotation", met to discuss modern research in the field of the rotation of the Earth with particu lar emphasis on the role of new observational techniques in this work. The use of these techniques has prompted a new look at the definitions of the traditional reference systems and the concepts of the rotation of the Earth around its center of mass. Specific topics discussed were time, polar motion, reference systems, conventional radio interferometry, very'long baseline interferometry (VLBI), Doppler satellite methods, satellite laser ranging, lunar laser ranging, and geophysical research concerning the Earth's rotation. Improvement in the accuracy of the observations is a key to possible solutions of the many unsolved problems remaining in this field. It appears that such improvement, using both classical and new techniques, is forthcoming in the near future. This will surely contribute to a better understanding of some of the long-standing questions concerning the rotation of the Earth around its center of mass and lead to an improved knowledge of the rotating, deformable Earth. This volume contains the papers presented at IAU Symposium No. 82 as well as the discussions provoked by these papers. It is hoped that it captures the principal points of the meeting and that it will contribute not only to a better understanding of existing problems, but also to future research in time and the Earth's rotation.