science

Geocentric Datum of Australia 1994

Geocentric Datum of Australia 1994 is a science 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 Geocentric Datum of Australia 1994 rather than just read about it. In short: The Geocentric Datum of Australia 1994 (GDA94) is a geodetic datum covering the Australian continent. Details of this datum are provided by the GDA94 Technical Manual.

Key takeaways

Geocentric Datum of Australia 1994 belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Geocentric Datum of Australia 1994 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Geocentric Datum of Australia 1994 from memory before moving on to harder problems.

Reference excerpt

The Geocentric Datum of Australia 1994 (GDA94) is a geodetic datum covering the Australian continent. Details of this datum are provided by the GDA94 Technical Manual.

History The GDA94 datum was formalized in 1994, replacing the previous datums which were being used in Australia at the time, the Australian Geodetic Datum 1966 (AGD66) and the Australian Geodetic Datum 1984 (AGD84). Prior to 1966, maps in Australia were produced in miles using the Australian National Grid.

Map Grid of Australia 1994 At the same time as GDA94 was defined, a Universal Transverse Mercator coordinate system called the Map Grid of Australia 1994 (MGA94) was also defined to replace the existing Australian Map Grid (AMG). This new map grid used the GDA94 datum and the GRS80 ellipsoid.

Relation to other datums For many users, GDA94 can be treated as being the same as the World Geodetic System 1984 (WGS84). However, where high accuracy is required, one must take into account that GDA94 is a static datum. GDA94 moves with the Australian continental plate. It is ITRF92 (using epoch 1994.0) and thus close to the WGS84 (G730) datum back in 1994, but since then has drifted at the rate of approximately 7 cm north east per year with a slight rotation. In 2000, the difference was approximately 45 cm. It is predicted that by 2020, the difference will be around 1.8 m. GDA2020 is based on a realisation of the ITRF2014 at epoch 2020.0, or 1 January 2020.

Modernisation The Intergovernmental Committee on Surveying and Mapping (ICSM) has proposed a two-stage plan to update the datum, given a working title of GDA2020.

Software for coordinate conversions DatumTran: https://web.archive.org/web/20160119145122/http://www.lpi.nsw.gov.au/surveying/geodesy/gda/datumtran_software AusDatumTool: http://www.binaryearth.net/AusDatumTool/index.php Check Australian Coordinate: https://www.egger-gis.at/automatic-projection-detection/checkcountryprojection/

References

Worked examples

Example 1 — a first encounter with Geocentric Datum of Australia 1994

Start with the simplest possible case. Write down what Geocentric Datum of Australia 1994 claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, 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 Geocentric Datum of Australia 1994 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 Geocentric Datum of Australia 1994 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 Geocentric Datum of Australia 1994

In research: Geocentric Datum of Australia 1994 appears in science 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 Geocentric Datum of Australia 1994 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: Geocentric Datum of Australia 1994 is common in secondary-school and first-year university syllabi. It links to neighbouring topics 1994 in Australia, Geodetic datums, Geography of Australia, so understanding it makes those chapters shorter.
In everyday life: Look for Geocentric Datum of Australia 1994 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 Geocentric Datum of Australia 1994 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Geocentric Datum of Australia 1994 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 Geocentric Datum of Australia 1994 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Geocentric Datum of Australia 1994 in simple terms?

The Geocentric Datum of Australia 1994 (GDA94) is a geodetic datum covering the Australian continent. Details of this datum are provided by the GDA94 Technical Manual.

Why does Geocentric Datum of Australia 1994 matter?

Because it connects several science 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 Geocentric Datum of Australia 1994?

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 Geocentric Datum of Australia 1994.