IN SHORT: The circular map was created in 1696 by a French astronomer, not in 1500 by the Renaissance artist Leonardo da Vinci. And it shows a “polar projection world map” highlighting the planet's lines of latitude and longitude – not a flat Earth.
“Flat earth map from Leonardo Da Vinci from around 1500,” a typical caption reads. “But NASA keep lying!”
Nasa is the National Aeronautics and Space Administration, the US government’s space programme.
Leonardo da Vinci was an Italian painter, sculptor, architect, scientist and engineer who lived from 1452 to 1519. He was a major figure in the European Renaissance. The Renaissance, French for “rebirth”, invigorated European art and ideas for around three centuries, from the 1300s to the 1500s.
Da Vinci is probably best known for painting the Mona Lisa. But his interests and knowledge extended into areas that put him ahead of his time – such as his study of human anatomy and his inventions, which included a flying machine.
But did he, two years earlier, make a “flat earth map” of the entire world?
Polar projection map from 1696
“This 1696 polar projection world map by Jacques Cassini (1677–1756) is the replica and only surviving representation of the large, 7.80-meter diameter planisphere by his father, Jean-Dominique Cassini (1625–1712),” its description reads.
“The first director of the Paris Observatory, the elder Cassini had designed the planisphere on the floor of one of the observatory’s towers, using astronomical observations performed by correspondents of the Academy of Sciences.”
A planisphere isn’t a ‘flat earth map’
On Facebook, a closer look at the map reveals that it’s titled, twice, “Planisphere terrestre”. That roughly translates, from Latin and Italian, as “terrestrial planisphere” or “planisphere of Earth”.
Because Earth is spherical, it’s difficult to produce accurate maps of the whole planet. It’s a bit like peeling an orange and then forcing the peel into the shape of a rectangle.
To get around this problem, several different projections of Earth are used to create maps. But none of them are perfect. The popular Mercator projection, for example, makes the land masses in the far south and far north seem far bigger than they actually are.
Cassini’s planisphere was another solution to the mapping problem. But it was also meant to show the lines of latitude around Earth. These imaginary but accurately measured lines were essential to the navigation of ships across oceans during a time of expanding European trade and colonisation.
In 1696, longitude – the lines from north to south – was difficult to calculate.
As the US Library of Congress explains: “The longitudinal measurements on the map are less accurate, as the determination of longitude remained problematic until the installation on ships, in the second half of the 18th century, of marine chronometers.”
The map wasn’t made by Leonardo da Vinci in 1500, and doesn’t show a flat Earth. It’s a planisphere – a “polar projection world map” – made by Jacques Cassini nearly 200 years later, in 1696.
The Greek philosopher Aristotle argued that Earth was spherical more than 2,000 years ago.
A few centuries later, the North African mathematician Eratosthenes not only proved that Earth was a sphere, but was able to roughly calculate the planet’s size. See a video of well-known science educator Carl Sagan explaining how Eratosthenes did it.
In 1500, Europeans such as Leonardo da Vinci had limited knowledge of the world’s geography. Da Vinci could not have drawn Africa and Eurasia as accurately as Cassini did 200 years later. And he couldn’t have drawn North and South America at all.
Earth isn’t flat. But it’s not round either – or, even, a sphere. Close observations have led scientists to describe the shape of our planet as “an irregularly shaped ellipsoid”. Its roughly spherical shape is constantly being distorted by, for example, its rotation around its axis, as well as its high mountains and deep ocean trenches.
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