## What Is The Circumference Of The Earth?

The circumference of the Earth is 40,075 km, and the Greek geographer Erastosthenes was the first person to estimate the Earth's circumference nearly accurately. Before Erastosthenes, other scholars had attempted to estimate the figure, but their methods were not recorded, and their estimations were far from accurate. With developments in technology, earth’s measurements, including the circumference have been accurately measured.

## Erastosthenes’ Measurement

Erastosthenes of Cyrene (present-day Libya) was a renowned Mathematician and geographer in Athens and Egypt. Having been well educated in Athens, he went to Egypt on the invitation of Ptolemy III, becoming the chief librarian of the Library of Alexandria. Erastosthenes' curiosity on the circumference of the Earth began with a text detailing the unusual summer solstice which had occurred in Syene, Egypt, where sunlight would shine directly overhead, and no shadows would stem from the column. He observed that at the same time in Alexandria, the column had shadows. It was from these observations that he was able to deduce that the Earth is curved and calculate the first estimate of the Earth’s circumference.

Armed with the relevant mathematical equations, he set out to determine the distance from Alexandria to Syene using stadia. Because of the uncertainty of stadia and limited technology, his measurement was slightly off the mark but was astoundingly accurate for his time. Erastosthenes, along with his other accomplishments, is credited with introducing the geography discipline and his contributions to mathematics.

## Earth’s Measurements

With a circumference of 40,075 km, Earth is the fifth largest of the planets in the Solar System. The meridional circumference that is from pole to pole is 40,008 km. The difference is caused by the flattening of the poles, such that the Earth has an oblate spheroidal shape. Earth’s rocky mantle and metallic core make it the densest planet, at 5.513 grams per cubic centimeter. Earth’s volume is estimated at 1 trillion cubic kilometers.

Earth’s surface area is an estimated 510 km2, and about 29% of the area is land while the other 71% consists of water. The composition of the Earth's atmosphere is 78% of nitrogen and 21% oxygen.

## Lowest And Highest Elevations On Earth

Rising to 29,029 feet (8,848 meters) is the highest peak above sea level on earth, Mt Everest in Asia. The most distant point from the Earth’s center is the Chimaborazo Mountain in Ecuador at 6, 267 meters (20,561 feet). The peak is the farthest point from the center of the Earth because of the oblate shape of Earth and its proximity to the equator. The lowest elevation on land is the Dead Sea, at 1,369 feet (417.27 meters) below sea level. The Pacific Ocean's Mariana Trench is the lowest point in water at 11, 034 meters (36,200 feet) below sea level.

## Other Facts About The Earth

The circumference of Earth varies depending on the method used to measure it. The measurement around the equator and from pole to pole differs because Earth is not a perfect sphere rather it bulges at the equator and flattens at the poles.

Earth, unlike other planets, has only one moon while a total of 166 moons in the solar system have been identified.

Earth rotates around the north-south path once in approximately 24 hours. The 24 hours form the basis of the clock system used worldwide. Earth moves in an apparent diurnal motion, where at a fixed position in the earth, the sky rather than Earth appears to be rotating.