We are independent & ad-supported. We may earn a commission for purchases made through our links.
Advertiser Disclosure
Our website is an independent, advertising-supported platform. We provide our content free of charge to our readers, and to keep it that way, we rely on revenue generated through advertisements and affiliate partnerships. This means that when you click on certain links on our site and make a purchase, we may earn a commission. Learn more.
How We Make Money
We sustain our operations through affiliate commissions and advertising. If you click on an affiliate link and make a purchase, we may receive a commission from the merchant at no additional cost to you. We also display advertisements on our website, which help generate revenue to support our work and keep our content free for readers. Our editorial team operates independently of our advertising and affiliate partnerships to ensure that our content remains unbiased and focused on providing you with the best information and recommendations based on thorough research and honest evaluations. To remain transparent, we’ve provided a list of our current affiliate partners here.

What is Geodesy?

By Caitlin Kenney
Updated May 17, 2024
Our promise to you
WiseGeek is dedicated to creating trustworthy, high-quality content that always prioritizes transparency, integrity, and inclusivity above all else. Our ensure that our content creation and review process includes rigorous fact-checking, evidence-based, and continual updates to ensure accuracy and reliability.

Our Promise to you

Founded in 2002, our company has been a trusted resource for readers seeking informative and engaging content. Our dedication to quality remains unwavering—and will never change. We follow a strict editorial policy, ensuring that our content is authored by highly qualified professionals and edited by subject matter experts. This guarantees that everything we publish is objective, accurate, and trustworthy.

Over the years, we've refined our approach to cover a wide range of topics, providing readers with reliable and practical advice to enhance their knowledge and skills. That's why millions of readers turn to us each year. Join us in celebrating the joy of learning, guided by standards you can trust.

Editorial Standards

At WiseGeek, we are committed to creating content that you can trust. Our editorial process is designed to ensure that every piece of content we publish is accurate, reliable, and informative.

Our team of experienced writers and editors follows a strict set of guidelines to ensure the highest quality content. We conduct thorough research, fact-check all information, and rely on credible sources to back up our claims. Our content is reviewed by subject-matter experts to ensure accuracy and clarity.

We believe in transparency and maintain editorial independence from our advertisers. Our team does not receive direct compensation from advertisers, allowing us to create unbiased content that prioritizes your interests.

Geodesy, sometimes called geodetics, is a science that applies mathematics to measure the size and shape of the Earth, the positions of points and regions on Earth, and the differences in its gravitational field. This science uses principles from physics, mathematics, and astronomy together with observation and modern technology to develop a spatial reference system. Geodesy also studies the movement of the Earth’s crust, polar motion, and tides. The work of geodesists includes giving points on Earth exact coordinates, precisely measuring the distances, angles, and heights between points, and looking at how and why the Earth’s surface has changed over different periods of time.

Many important fields of work depend on geodesy to function properly. Ships and planes use global positioning systems (GPS), maps, and other navigation systems based on geodetic data to ensure that they land in the correct place, avoid dangerous lanes of travel, and take the quickest and most fuel efficient routes. Scientists from other fields, such as oceanographers or paleontologists, use geodetic data to examine the forces that cause change in Earth’s surface features, or topography. The military has long used geodesy to determine exact points for pinpointing locations, controlling artillery, navigating, and, later, tracking satellites and directing missiles.

Some historians claim that the study of geodesy began with the ancient Greeks’ early attempts to measure the size of the Earth. The first earnest attempt at taking accurate measurements, as far as it is known, was pursued by the Greek scholar Eratosthenes in the third century BC. By measuring the angles of shadows at two points on Earth at a particular time of the year, measuring the distance between the points, and assuming that the two points lie on an exact north-south plane, Eratosthenes was able to make an astonishingly accurate approximation of the Earth’s circumference. Despite some faulty data, the scholar estimated the Earth to be 25,000 miles (40,233 km). Today, geodesists agree that the Earth is roughly 24,901 miles (40,074 km) at the Equator.

Several other ancient Greeks used similar methods, measuring the angles of stars to two points on Earth, to make their own estimates and maps. The field of geodesy continued to evolve throughout the centuries, meeting with rapid advancement in the 17th century AD. During this period, the telescope was developed, allowing greater accuracy in measuring angles to objects in space; logarithms were invented, allowing greater computational efficiency; and triangulation was discovered as a method of determining the location of a point. Using this new technology, French-Italian scholar Giovanni Domenico Cassini discovered that the Earth was not spherical, as it had previously been assumed, but elliptical, or egg-shaped.

Several techniques can be used to examine the three-dimensional shape and scope of the Earth, as well as the positioning of the gravitational field. Most can be put under the umbrella of land surveying, satellite imaging, and applied mathematics based on data gathered by the first two methods of observation. Because the Earth is highly irregular in shape, geodesists use a mathematical model of the Earth known as a reference ellipsoid to efficiently measure the Earth. The ellipsoid can be completely smooth, unlike the geoid, another model which represents the irregularity of the figure of the Earth and the changes in gravitational pull. While, the ellipsoid maintains the general shape of the planet, which is flatter at the poles and wider at the equator, the lack of topographical complexity makes computations far simpler.

WiseGeek is dedicated to providing accurate and trustworthy information. We carefully select reputable sources and employ a rigorous fact-checking process to maintain the highest standards. To learn more about our commitment to accuracy, read our editorial process.
Discussion Comments
WiseGeek, in your inbox

Our latest articles, guides, and more, delivered daily.

WiseGeek, in your inbox

Our latest articles, guides, and more, delivered daily.