摘要:

Comet Halley, which is again visiting our solar neighborhood during fall 1985 and spring 1986, was seen with a telescope for the first time on August 15, 1682, by John Flamsteed, assistant observer at the Greenwich Observatory near London. Jean Picard and Philippe de La Hire saw it at Paris on August 26, 1682, shining as if it were a star of the second magnitude. Johannes Hevelius, at Danzig (now Gdansk, Poland), estimated the length of its tail at that time at 12°‐16°. The astronomers of that epoch considered the comet to be a new one that should be added to the list of all those previously observed. The English astronomer Edmond Halley, who was haunted by the idea that all comets need not necessarily describe parabolic orbits, calculated the orbital elements of the new comet and compared them to those of comets that had appeared in 1607 and in 1531 (the heavenly paths of which had been noted by Johannes Kepler and by Christian Severin Logomontanus and Petrus Apianus, respectively). Upon examining the data in Table 1, one can not but be surprised by the near identical value of the eleme

ISSN:0002-8606    

DOI:10.1029/EO067i011p00129

年代:1986

数据来源: WILEY

摘要:

The tragic explosion of the space shuttleChallengerhas caused a delay of at least 13 months to the European Space Agency/National Aeronautics and Space Administration (ESA/NASA) cooperative mission Ulysses, previously known as the Solar Polar Mission. Ulysses was scheduled for launch in May 1986. The launch of the Hubble Space Telescope, in which ESA is a cooperative partner, is certain to be delayed beyond the October 1986 launch date.As Eos went to press, the Giotto spacecraft, which has been on its way to Comet Halley since July 1985, was performing well, according to ESA. All investigator groups participated in operation rehearsals at the European Space Operations Centre in Darmstadt, Federal Republic of Germany, in preparation for the cometary encounter, which occurred near midnight (UT) on March 13, 1986.

ISSN:0002-8606    

DOI:10.1029/EO067i011p00130-01

年代:1986

数据来源: WILEY

摘要:

The following hearings and markups have been tentatively scheduled for the coming weeks by the Senate and House of Representatives. Dates and times should be verified with the committee or subcommittee holding the hearing or mark up; all offices on Capitol Hill may be reached by telephoning 202‐224‐ 3121. For guidelines on contacting a member of Congress, see AGU's Guide to Legislative Information and Contacts (Eos, August 28, 1984, p. 6

ISSN:0002-8606    

DOI:10.1029/EO067i011p00131-01

年代:1986

数据来源: WILEY

摘要:

The objectives of this book are set out clearly in its preface, wherein Fred Whipple states,This book tells the story, step by step, from ancient times to the present era, of our progress in understanding comets . . . The first fourteen chapters present clues and theories developed before the twentieth century; the remaining chapters provide up‐to‐date information regarding the nature of comets, their origin, and their possible relation to life on Earth. Comets appear to be the most primitive bodies in the Solar System and may even have played an important role in making life on Earth possible. Later chapters center on these issues, on space missions to comets, and on the general problems and significance of comets, including the hazards they may repres

ISSN:0002-8606    

DOI:10.1029/EO067i011p00132-03

年代:1986

数据来源: WILEY

摘要:

The AGU Committee on the History of Geophysics (CHG) was created in 1982 following recommendations of an ad hoc committee, and its main task to date has been to promote the preservation and study of the history of geophysics. Toward that goal, it encouraged appointment of an Eos editor for history and later suggested an annual series, “History of Geophysics,” to consist of historyrelated articles from AGU publications. It has started a newsletter, and it has encouraged, sponsored,‐ coordinated, and recorded an increasing number of history talks at AGU meetings.The responsibility for this work has fallen primarily on five CHG officers. The Eos history editor, C. Stewart Gillmor (Wesleyan University, Middletown, Conn.), solicits and edits history articles, arranges their review by referees, and also selects and edits material for the History of Geophysics series. The newsletter editor, Sam Silverman, single‐handedly (with help from an Osborne PC) produces our newsletter. A meeting coordinator, initially Marty Walt of Lockheed Laboratories (Palo Alto, Calif.) and then (until recently) Pat Taylor of the National Aeronautics and Space Administration Goddard Space Flight Center (Greenbelt, Md.), helps arrange, publicize, and record history talks at AGU meetings. The secretary, Jim Heirtzler (Woods Hole Oceanographic Institution, Woods Hole, Mass.) is in charge of minutes of meetings, correspondence, and the mailing of the newsletter. Finally, as chairman, I carry overall responsibility for the activities of CHG, initiate new ventures, and often back up other officers in thei

ISSN:0002-8606    

DOI:10.1029/EO067i011p00135-01

年代:1986

数据来源: WILEY

摘要:

The First International Symposium on Precise Positioning With the Global Positioning System (GPS) was held in Rockville, Maryland from April 15 to April 19, 1985; 600 participants from 31 countries attended. Sponsors included the International Union of Geodesy and Geophysics, the International Association of Geodesy, the Defense Mapping Agency (DMA), and the National Oceanic and Atmospheric Administration (NOAA) in cooperation with the American Society of Civil Engineers. GPS uses the NAVSTAR (an acronym for Navigation and Satellite Timing and Ranging) satellite system developed by the Department of Defense (DOD).Although this symposium was limited to precise positioning with GPS, the scope of precise positioning was left open. Without a doubt, precise relative positioning with L band carrier phase measurements was the most important topic. Also included were certain high‐accuracy applications of pseudorange measurements, such as orbit determination, time transfer, and navigation. Administration, policy, hardware, software, processing, and applications in these areas were also covered. Intentionally left out were areas in which high positional accuracy was not important (e.g., commercial aviation). Attendees presented 89 papers, which were organized into 15 sessions covering nine subject areas: overview, status, and policy; GPS time and orbits; user equipment; user equipment testing; modeling and processing; applications; survey positioning results; practical aspects of geodesy; and dynamic positionin

ISSN:0002-8606    

DOI:10.1029/EO067i011p00136

年代:1986

数据来源: WILEY