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Upcoming Events
all-day New Year’s Day Holiday @ City of Ukiah Civic Center
New Year’s Day Holiday @ City of Ukiah Civic Center
Jan 2 all-day
New Year's Day Holiday @ City of Ukiah Civic Center | Ukiah | California | United States
The City of Ukiah Civic Center will be closed to observe the New Year’s Day Holiday.
11:00 am Airport Commission @ OLD F.S.S. Building
Airport Commission @ OLD F.S.S. Building
Jan 2 @ 11:00 am – 1:00 pm
Airport Commission @ OLD F.S.S. Building | Ukiah | California | United States

Observatory Park


City of Ukiah Observatory Park, International Latitude Observatories, Northern Hemisphere

Mendocino County’s Legacy in the World of Science

Landmarks are not frozen in time. They are not like prehistoric insects preserved in fossilized amber. They are living and their heritage is nurtured by community commitment and individual involvement.

In 2014 Observatory Park was dedicated to the people of Ukiah. From that day forward a commitment was made to preserve the Ukiah Latitude Observatory and for the park to become part of Ukiah’s living heritage.

Be a part of the heritage and come enjoy this unique park located at the 400 block of Observatory and Luce Avenues.

Project History

International Latitude Observatories, Ukiah Observatory Park, Northern Hemisphere

The International Latitude Observatories were a system of (originally) six observatories located near the parallel of 39° 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.

United States Coast and Geodetic Survey joined the International Polar Motion Service program in 1897 to study the precession, or “wobble” of the Earth’s axis, and its effect on measures of latitude. Six separate observatories were created along the parallel 39° 08′ north latitude. The alignment of all six stations along the parallel helped the observatories to perform uniform data analysis.

Economic difficulties and war caused the closings of some of the original stations, though a newer station was created in Uzbekistan after World War I. The various 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 has been applied to studies of polar motion, the physical properties of the Earth, climatology and satellite tracking and navigation.

Ukiah Observatory

Ukiah Latitude Observatory, City of Ukiah Park, Northern Hemishpere, Historic

Ukiah Latitude Observatory Was Built in 1899

The small size of the building (12 feet square) and the esoteric character of the work that took place within speak modestly of the international importance of the landmark. The research provided all data used in polar motion studies for decades, and fostered international cooperation which transcended the differences between man during times of war and international strain.

The city acquired the property in 1991 but the observatory and adjoining land was closed to the public until March 2014. A $54,000 grant from the California Land and Water Conservation Fund, along with matching funds from the City of Ukiah, made the improvements necessary to reopen the park.

Observatory Park Oak Tree, Ukiah, CAA large heritage Valley Oak anchors the north end of the park. Spreading before it is a large grassy field providing an unobstructed view of the iconic tree.

Ukiah’s first Pétanque court was completed in 2010 for the game of boules, or balls, closely related to bocce by the Redwood Empire Boules Club.

A peace pole, dedicated to Erica Enzer, an international peace activist and former member of the Ukiah War Resistor’s League is located adjacent to the Grove of Nations (trees representing each of the regions where the latitude observatories were located).

Labyrinth in Observatory Park, Ukiah, CAThe park has had improvements made before its public opening, including the restoration of the historic observatory and a labyrinth (pictured at left) installed in 2005.

The former observer’s residence has been used by Ukiah Unified School District since 2011 for the Community Transition Program which assists special needs students aged 18 to 22.

Photo Gallery

Get Involved

For more information about how you can become involved in preserving the Ukiah Latitude Observatory and our community’s cultural heritage, contact :

Martin Bradley

City of Ukiah

411 W. Clay St

Ukiah, CA 95482



Observatory Park News & Events

Observatory Park: Tours of Earth & Sky

Observatory Park is the home of the Ukiah Latitude Observatory, one of five international latitude observatories around the world operated from 1899 to 1982. The City of Ukiah offers several events associated with this unique park:

  • Tours of Earth and Sky: Park Interpreter Martin Bradley will host a lecture series in the Ukiah Civic Center’s Council Chambers with guest speakers offering talks on astronomy and the natural sciences.
  • Docent Tours of the Observatory and park are scheduled by appointment for small groups and individuals on Thursday, Friday, and Saturday.
  • Open Skies are scheduled periodically where amateur astronomers bring their telescopes, experience, and knowledge to explore the moon, planets, and deep sky wonders.

There is no charge for these events. Reservations are required and young children are welcome with a supervising adult. If you have questions, are interested in upcoming lectures, would like to schedule a tour, or are interested in finding out about the public viewing nights, call 707-467-5768.

News and Event Posts

Ukiah Latitude Observatory

City of Ukiah WELCOME TO OBSERVATORY PARK Observatory Park was deeded to the City of Ukiah in 1991 by the US Department of Commerce after 83 years of continuous astronomical observation by the U.S. Coast and Geodetic Survey. The small wood-framed structure at the south entrance to the park on Observatory Avenue played a key role in the scientific investigation of the Earth’s rotation. In 1898, the International Geodetic Association established a network of observatories to measure the wobble of the planet on its axis by plotting the locations of specific stars. This spot in Ukiah was chosen together with sites in Gaithersburg Maryland, Italy, Japan, and the Russia. All five lay along the same latitude (39° 8’ N). The park is preserved as an open space “for the quiet enjoyment of the residents of Ukiah” and to provide clear ground and satellite views of small brass survey monuments located on the grounds. Though technology rendered the nightly observations by resident astronomers unnecessary, the survey monuments are still referred to today as benchmarks to determine aberrations in of the earth’s motion.
Ukiah Latitude Observatory
Ukiah Latitude ObservatoryDec 2, 2017 @ 9:50am
Supermoon time again.In December, the full moon rises earlier than other times of year, as the sun sets later in the winter. Full moons are always opposite the sun, and it occupies the spot where the sun would be June. It will rise and be high in the sky til dawn.
EDIT: Good article, but...
(See comments below).
Ukiah Latitude Observatory
Ukiah Latitude ObservatoryNov 25, 2017 @ 9:26pm
I need to remember to post these for the curious; now that night comes early and dawn is late and the morning and evening planets grace the sky. From Sky & Telescope.
Ukiah Latitude Observatory
Ukiah Latitude ObservatoryNov 25, 2017 @ 9:15pm
Great fall photo of the park taken from The Pétanque court today. Thanks Mickey Coughlin!
Ukiah Latitude Observatory
Ukiah Latitude ObservatoryNov 20, 2017 @ 8:11pm
Last week Dave Turner and I went down to Citrus College in Glendora to visit the Frank Schlesinger Personal Archives. Specifically, to scan the old photographs. Schlesinger was the first astronomer in Ukiah and built the latitude observatory in 1899. In 2014, his personal library was transferred to us from Citrus College, except a few volumes they kept. We scanned the photos and took photos of the title page of the remaining photos to compile a complete catalog. More to come of this archiving project. Contact us if you are interested in helping!
Ukiah Latitude Observatory
Ukiah Latitude ObservatoryNov 20, 2017 @ 11:12am

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