Eratosthenes expertized in various professions such as mathematics,
geography, poetry, astronomy, and music theory. He is predominantly known for
his contribution to the study of astronomy as he is the first individual to
calculate the circumference of the Earth accurately. In addition, he was the
first astronomer that calculated the tilt of the Earth’s axis. Adding to his
contribution to the study of Astronomy, he had also calculated the distance
from the Earth to the Sun and introduced the concept of leap day. Furthermore with
his understanding of geography during his era, he was able to form the first
map of the world with parallels and meridians.
Apart from astronomy, he had invented scientific chronology
by organizing events after the siege of Troy. Eratosthenes had contributed to
mathematics as well, particularly to the study of number theory. He presented a
technique to pinpoint prime numbers called the sieve of Eratosthenes.
Throughout his life, Eratosthenes has contributed valuable information to science.
Eratosthenes calculated the circumference of the Earth by
measuring the altitude of the sun at Alexandria during noon. Using the known
fact that on June 21st at Syene the sun is directly overhead. The
zenith distance at Syene was 0 degrees while at Alexandria it was 7 degrees. In
addition to this Eratosthenes was aware of the distance between Alexandria and
Syene, hence he used geometry and the zenith to calculate the circumference of
the Earth.
Eratosthenes was able to approximate the circumference of
the Earth to a percent error of 16.3% from what the current measurements is
today. He calculated the size of the Earth to be approximately 46,620 km.
I believe it was a success due to the incredible accuracy
considering the time Eratosthenes calculated the circumference of the earth. Despite
the lack of accurate tools and measurements he was able to approximate the
circumference with a high degree of accuracy. In addition he was the first astronomer
to calculate the Earth’s circumference with much accuracy. By using the method
of calculation that Eratosthenes used alongside with the data available today,
the result would be 40,074 km which has a remarkable precision of 0.16%.
Sources:
http://www.britannica.com/EBchecked/topic/191064/Eratosthenes-of-Cyrene
http://www.math.wichita.edu/history/men/eratosthenes.html
