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Earth in Different Dimensions
Round?
Or flat?
Observing the World
observation
the key first step to ALL science
driven by curiosity
a process of discovery
answer questions about how the world works
knowledge improves quality of life
Eratosthenes
(Egypt, 235 B.C.)
On June 21 (summer solstice), midday sun
directly overhead, shining down a deep well in
the city of Syene (Aswan)
Angle of shadow made by sun shining on a
monument at midday on June 21 in Alexandria
was 7o21’
Alexandria lies ~5000 stadia to the north of
Aswan (~500 miles)
Calculate circumference (C) using simple math:
360o/7.2o= C/500 miles; C= 50 x 500 miles =
25,000 miles
Remarkable agreement with actual figure of
24,862 miles (40,010 km) – WOW.
a well in Syene
a shadow cast by a
monument in Alexandria
7°12' = 7.2°
~5000 stadia = 500 mi
the Sun's rays
