Transcript Early Greek Astronomy And Ptolemy’s Almagest Eratosthenes • Finds the size of the earth within 5%

Early Greek
Astronomy
And
Ptolemy’s
Almagest
Eratosthenes
• Finds the size of the earth within 5%
o
500 m iles
7.5

o
2 ( Radiusof Earth)
360
REarth
360  500

 3820 miles
2  7.5
Actual radius  3950m iles
Error about 3.5%
Important Ratio
Distance to the Moon
• If the sun is a point source
Trigonometry Tables in the
Almagest
• Not in terms of our trig functions sine,
cosine, tangent, etc.
Greek Number System