astronomy

International Latitude Service

International Latitude Service is a astronomy topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand International Latitude Service rather than just read about it. In short: The International Latitude Service was created by the International Geodetic Association in 1899 to study variations in latitude caused by polar motion, precession, or "wobble" of the Earth's axis. In 1891, at the meeting of the Permanent Commission of the International Geodetic Association in Florence, Wilhelm Foerster referred to the discovery by Seth Carlo Chandler of the polar motion predicted by Leonhard Euler…

Key takeaways

International Latitude Service belongs to astronomy; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect International Latitude Service to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of International Latitude Service from memory before moving on to harder problems.

Reference excerpt

The International Latitude Service was created by the International Geodetic Association in 1899 to study variations in latitude caused by polar motion, precession, or "wobble" of the Earth's axis. In 1891, at the meeting of the Permanent Commission of the International Geodetic Association in Florence, Wilhelm Foerster referred to the discovery by Seth Carlo Chandler of the polar motion predicted by Leonhard Euler in 1765 and his impact on the determination latitudes. He proposed that the International Geodetic Association implement a systematic study of this important phenomenon. In 1895, the creation of the International Latitude Service was decided by the International Geodesic Association. Its central office was based in Potsdam and headed by Friedrich Robert Helmert. Regular observations began in 1899. After 1916, the operations of the International Latitudes Service continued under the aegis of the Reduced Geodetic Association among Neutral States presided by Raoul Gautier director of Geneva Observatory. The original International Latitude Observatories were a system of six observatories located near the parallel of 39° 08' north latitude. The alignment of all six stations along the parallel helped the observatories to perform uniform data analysis. The original six observatories were located in:

Gaithersburg, Maryland, United States Cincinnati, Ohio, United States Ukiah, California, United States Mizusawa, Iwate, Japan Charjui, Turkmenistan Carloforte, Italy 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 closings of some of the original stations, though a newer station was created in Uzbekistan after World War I. 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. The final six observatories were located, in order of Longitude (E to W), in:

Gaithersburg, Maryland, USA, Gaithersburg Latitude Observatory: Cincinnati, Ohio, USA: Ukiah, California, USA: Mizusawa, Japan, National Institutes of Natural Sciences National Astronomical Observatory of Japan, Mizusawa VERA Observatory: Kitab, in Uzbekistan: Carloforte, Italy: The ILS was renamed International Polar Motion Service (IPMS) in 1962. It was replaced when the International Earth Rotation Service (IERS) was established in 1987.

See also List of astronomical observatories

References

Further reading Proverbio, E. (2000). "The Period of Organization of the International Latitude Service: 1889–1899". International Astronomical Union Colloquium. 178. Cambridge University Press (CUP): 121–138. doi:10.1017/s0252921100061261. ISSN 0252-9211.

External links National Park Service - The history of the Gaithersburg Observatory in Maryland, and the overall project.

39°08′12.51″N 77°11′55.85″W 39°08′20.45″N 84°25′24″W 39°08′14.26″N 123°12′42.54″W 39°08′6″N 141°07′54″E 39°08′0″N 66°52′54″E 39°08′13.76″N 8°18′41.90″E

Illustrations

Worked examples

Example 1 — a first encounter with International Latitude Service

Start with the simplest possible case. Write down what International Latitude Service claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In astronomy, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to International Latitude Service before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about International Latitude Service ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of International Latitude Service

In research: International Latitude Service appears in astronomy research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses International Latitude Service in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: International Latitude Service is common in secondary-school and first-year university syllabi. It links to neighbouring topics Astronomical observatories in California, Astronomical observatories in Italy, Astronomical observatories in Japan, so understanding it makes those chapters shorter.
In everyday life: Look for International Latitude Service outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study International Latitude Service in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what International Latitude Service means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain International Latitude Service out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is International Latitude Service in simple terms?

Why does International Latitude Service matter?

Because it connects several astronomy ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study International Latitude Service?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on International Latitude Service.