Eratosthenes and the system of the world (2024)

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Eratosthenes and the system of the world? ›

Studying the earth

Eratosthenes method was very simple; he measured the length of a shadow from a vertical stick of a known height in two cities on the same day. The ratio between the north-south distance between the two cities and the angles measured gave a ratio which allowed Eratosthenes to calculate the size of the Earth.

Eratosthenes was a Greek mathematician who is famous for his work on prime numbers and for measuring the diameter of the earth.

If we accept the account of Strabo that Eratosthenes measured the circumference of the earth as 252,000 stadia, the circumference would be 24,662 miles, and the polar diameter 7,850 miles-only 50 miles short of the true polar diameter. This is considered to be one of the first great triumphs of scientific calculation.

While serving as the head librarian and scholar at the Library of Alexandria, Eratosthenes wrote a comprehensive treatise about the world, which he called "Geography." This was the first use of the word, which in Greek means "writing about the world." Eratosthenes' work introduced the concepts of torrid, temperate, and ...

Eratosthenes erected a pole in Alexandria, and on the summer solstice he observed that it cast a shadow, proving that the Sun was not directly overhead but slightly south. Recognizing the curvature of the Earth and knowing the distance between the two cities enabled Eratosthenes to calculate the planet's circumference.

The first person to determine the size of Earth was Eratosthenes of Cyrene, who produced a surprisingly good measurement using a simple scheme that combined geometrical calculations with physical observations.

Today, most scientists set the earth's circumference at 40,096 kilometers (24,901 miles). This gives Eratosthenes' estimate less than a one percent error—an excellent approximation of the earth's circumference.

What is Eratosthenes famous for? Eratosthenes measured Earth's circumference mathematically using two surface points to make the calculation. He noted that the Sun's rays fell vertically at noon in Syene (now Aswān), Egypt, at the summer solstice.

The map is sparse but sophisticated, and noteworthy for its early use of parallels and meridians in a grid system. Eratosthenes drew a main parallel running east- west through Rhodes, and a main meridian running north-south, again with Rhodes at its center.

How far did Eratosthenes think the Sun was? ›

With a stade of 185 m (607 ft), 804,000,000 stadia is 149,000,000 km (93,000,000 mi), approximately the distance from the Earth to the Sun. Eratosthenes also calculated the Sun's diameter. According to Macrobius, Eratosthenes made the diameter of the Sun to be about 27 times that of the Earth.

Considering time measurement, he did not need it. He used two cities on approximately the same longitude and measured shadows at noon. Noon is determined when the shadow is shortest, and one does not need any clock for this.

The Ancient Egyptians did not calculate the circumference of the Earth. It is believed that the Greek mathematician Eratosthenes was the first to do so in the 3rd century BCE. He used the angles of shadows cast by the sun at two different locations to calculate the circumference of the Earth.

Eratosthenes (l. c. 276-195 BCE) was a Greek astronomer, geographer, mathematician, and poet best known for being the first to calculate the circumference of the earth and its axial tilt.

It is unknown if Eratosthenes competed in athletics, but the name recognized his diverse field of knowledge and expertise. He was also nicknamed Beta for his achievements, yet they were always just short of other great leaders in the field.

If this remarkable result had been his only achievement, he would still have been considered one of the greatest thinkers ever, but Eratosthenes wasn't done. By studying the Sun's apparent path across the skies, he was able to calculate the Earth's tilt of about 23.5 degrees which is also insanely accurate.

Eratosthenes was able to measure the radius of the earth using the difference in measure- ments of shadow length at two locations directly north-south of each other on the same day. To use this method, you first must accept that the earth is round.

How did Eratosthenes estimate the size of Earth? They measured the angle of the Sun above the horizon at midday in two places with different latitude and used the angle to estimate the circumference of Earth.

Eratosthenes knew the distance between two cities, he had the angle of the sun measured in each city at local noon on the same day. Using trigonometry he was able to calculate fairly closely the radius of the earth, which gives the diameter and distance around. This was about 250 BC.

He watched the shadow of the gnomon on the day in question, and measured the length of the shadow at noon. The height of the stick and the length of the shadow allowed him to calculate the angle between the vertical at Alexandria (as indicated by the gnomon) and the direction of the Sun's rays at noon.