Eratosthenes

Early life: ❏ Born in 276 BC❏ Cyrene, Lybia ❏ Greek ❏ Went to the

gymnasium(school) ❏ Nick name was Beta,

or Pentathlos because he was always in second place in terms of his education, but was a well rounded student.

Education ❏ At age 6, he went to the gymnasium (a

school) ❏ Studied in Athens ❏ Was convinced to move to Alexandria

where he became the librarian ❏ Teachers

❏ Lysanias of Cyrene-scholar❏ Ariston of Chios-philosopher

❏ Studied under Zeno❏ Callimachus-Poet, Scholar

Adult life: ❏ Worked math

❏ Found the circumference of the Earth (or tried) his units were the size of a stadium he lived by so no one knows how accurate his measurement really was

❏ Made the sieve number which is now important for number theory

❏ Worked on music❏ Wrote books on comedy, history, constellations, geography

and philosophy

Major accomplishments in astronomy:

❏ Invention of the armillary sphere❏ Size of the earth ❏ Distance to the moon and distance to

the sun❏ Got a accurate answer to the tilt of the

earths axis❏ unknown as to how he got his

answer❏ Star map with 675 stars ❏ Suggested that there be an extra day

added to the calendar every 4th year.

Armillary sphere❏ Also called the spherical astrolabe ❏ Used to study stars, celestial bodies, and position

of the sun❏ Helped people navigate the ocean❏ Used in Asia, Islamic empire and by greeks ❏ Set of rings around a sphere❏ some rings mean the circles of heaven ❏ The position was calibrated by finding an object in

the sky and positioning it that way.

Size of the Earth:

https://www.youtube.com/watch?v=8On7yCU1EjQ The way in which he did this was he noticed that the sun would hit a certain certain object once a year on the same day. Then measured the distance from Alexandria to Syene. Since the sun was extremely far away he assumed that the suns rays were for the most part parallel. Then he came up with the angles created from these measurements and his answer is extremely close to the real deal. Using this measurement he created a map of the world based off of them.

Distance to the moon/sun❏ made these based off of lunar cycles for

both sun and moon❏ Were no where near as accurate as the

distance calculated for the earth❏ His guess for the sun was 136988092

km, and the real distance is 149,600,000 km

What was known at the time: ❏ A year is about 365 days

long-Egyptians ❏ The Earth is a sphere-

Pythagoras❏ The Earth rotates on an axis-

Heraclides ❏ Space is infinite-Plato❏ We move around the sun-

Philolous ❏ use of the sundial

What wasn’t known or incorrect❏ Don’t know that we are in a galaxy ❏ Sun is the center of the solar system-

Aristarchus ❏ Many planets orbit the earth-Heraclides

Things named after him:

❏ Eratosthenes crater, found on the moon

❏ A lunar period (3200-1100 MYA)

❏ And a seamount close to Cyprus.

Bibliography Images:French School, “Eratosthenes,” n.d. nndb.com, September 7, 2014.Luiza, untitled. 2011. http://karnerkapers.blogspot.com/, September 7, 2014“Athens,” www.cntraveller.com/, September 7, 2014.www.3villagecsd.k12.ny.us, September 5, 2014.“Armilitary Sphere” www.en.wikimedia.org, September 7, 2014.NASA, “Earth and Moon Image” www.mathtouchapp.com/, September 7, 2014.NASA, “Crater” www.en.wikimedia.org, September 7, 2014.Capuzzi, Mike. “Leap Year” www.mikecapuzzi.com, September 6, 2014. Content:

O’Connor, J.J. & Robertson, E.F. “Eratosthenes of Cyrene” 1999. www-history.mcs.st-and.ac.uk. September 5, 2014.

www.3villagecsd.k12.ny.us, September 5, 2014.

Arizona State University, “Eratosthenes Crater” 2010. www.nasa.gov. September 5, 2014.

Geologic Data Scale. www. sites.google.com/site/geologicdatascale. September 6, 2014

Gold, Ethan, “Meet Eratosthenes Seamount” 2012. www.nautiluslive.org. September 4, 2014.

Green, Nick, “Eratosthenes of Cyrene” www.space.about.com. September 5, 2014.

“Armilitary Sphere” www.innovateus.net. September 7, 2014.

Poulsen, Erling, “Astrolnomical Timeline” www.rundetaarn.dk. September 7, 2014