From Martin Bradley
The International Latitude Observatories were a system of (originally) six observatories located near the parallel of 39º 08’ north latitude. They were used to measure the variation in latitude that occurs as a result of the wobble of the Earth on its polar axis. The orginal six observatories were located in:
• Gaithersburg, Maryland
• Cincinnati, Ohio
• Ukiah, California
• Mizusawa, Japan
• Charjui, Turkestan
• Carloforte, Italy
The International Polar Motion Service program was created by the United States Coast and Geodetic Survey in 1899 to study the precession, or “wobble” of the Earth’s axis, and its effect on measures of latitude. Six separate observatories were created . The alignment of all six stations along the parallel helped the observatories to perform uniform data analysis. Twelve groups of stars were studied in the program, each group containing six pairs of stars. Each night, each station observed two of the star groups along a preset schedule and later compared the data against the measurements taken by the sister stations.
Economic difficulties and war caused the closing of some of the original stations. The stations continued to function until advances in computer technology and satellite observations rendered them obsolete in 1982. The data collected by the observatories over the years still has use to scientists, and had been applied to studies of polar motion, physical properties of the Earth, climatology and satallite tracking and navigation.
Continue to Ukiah International Observatory Index→
Update: The Jason Bradford interview of Bill McKibben on the Reality Report KZYX via Global Public Media (Transcript)→