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Earth's circumference, a key geographical and navigational concept, measures approximately 40,075 km equatorially and 40,008 km meridionally. The shape, an oblate spheroid due to Earth's rotation, affects mapping and navigation. Historical figures like Eratosthenes and Al-Biruni made early estimations, influencing units of measurement and exploration. Accurate circumference data remains crucial for modern geodesy and technology.

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## Earth's Circumference

### Equatorial Circumference

The distance around the Earth at the equator, approximately 40,075 kilometers

### Meridional Circumference

The distance from pole to pole on Earth, approximately 40,008 kilometers

### Deviation from a Perfect Sphere

Earth's rotation causes it to take on an oblate spheroid shape with a bulge at the equator and flattening at the poles, quantified by the "flattening" factor of roughly 0.3%

## Historical Measurements

### Eratosthenes' Estimation

In the 3rd century BCE, Greek scholar Eratosthenes estimated Earth's circumference by observing the differences in solar angles at Alexandria and Syene, calculating it to be about 250,000 stadia

### Influence on Units of Measurement

Earth's circumference has significantly influenced the development of units of length, such as the nautical mile and the meter

### Advancements in Measuring

Successors to Eratosthenes, such as Posidonius and Al-Biruni, continued to refine the measurement of Earth's circumference using trigonometry and observations of stars and mountains

## Impact on Exploration and Science

### Christopher Columbus' Mistake

Christopher Columbus underestimated Earth's size, leading to his mistaken belief that he had reached Asia when he had actually discovered the New World

### Importance in Modern Times

Precise measurements of Earth's circumference are vital for geodesy, navigation, and the standardization of measurement units, and have also enhanced cartography, navigation, and space exploration

Algorino

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