If Earth Is Round, the Mn Must be Round T 21
approximately 925 km (575 miles). Then he used the following formula to determine the
circumference of Earth.
575 miles (925 km) 28,750 miles (46,250 km)×
Although we now know that the circumference of Earth is 40,000 km (24,855 miles),
Eratosthenes’ calculation is remarkably close.
Another version of the story says that Eratosthenes got his idea by seeing the Suns
rays reach the bottom of a well rather than observing the shadow cast by a rod. Neverthe-
less, it is generally accepted that he calculated Earth's circumference as being approximately
25,000 miles, which is roughly accurate.
If Earth Is Round, the Moon Must be Round Too
It is quite reasonable to suppose that scholars like Eratosthenes were not the only ones
to realize that Earth was round. Certain phenomena—such as the fact that you cannot
see beyond the horizon, or that the top of the sail always appears first when a ship is
approaching—were obvious to people whose lives were closely related to the sea, and these
occurrences are inconceivable on a flat surface.
Ancient Greece, where Eratosthenes lived, was a maritime nation bordered by the
Ionian and Aegean Seas and located not far from the Mediterranean Sea. For that reason
alone, many seafaring Greeks may have sensed that the world might be round.
to the surface
of Earth
North pole
South pole
Sun’s rays
Eratosthenes’ calculation method
22 Prologue A Tale That Begins onthe Mn
On the other hand, when people
with good eyesight observe light striking
the Moon they should easily see that its
surface is spherical rather than flat. For
example, if you look at an enlarged pho-
tograph, there are clearly gradations at
the outer edge and the waxing or waning
border line. This wouldn't happen if the
Moon were flat.
Now, let’s return to the story of
Japan is an island country, sur-
rounded by the sea. This means that
even in ancient times, some Japanese
people probably recognized the existence
of the curved horizon and from that con-
cluded that Earth was round.
For example, when European
missionaries traveled to Japan in the
16th century, they tried to introduce their
scientific knowledge to the feudal lords
they found there. One item they presented
as a display of their knowledge was a
globe. However, contrary to the expecta-
tions of the Europeans, most Japanese
people did not show surprise at the sug-
gestion that the world was a sphere.
The fact that Japanese people have
gazed at and felt affection for the Moon
since ancient times is also apparent from
folklore, such as the story of the Moon
Rabbit. And although Otsukimi (moon-
viewing) festivals seem to have originated
in China, the custom of appreciating the Moon is said to have existed in Japan since the
J m o n period (approximately 14,000 BC to 400 BC). Most likely, it would have been recog-
nized then that the Moon was a sphere.
If Earth—like the Moon—is round and floats in space, then the idea that people should
live on both Earth and the Moon is a natural conclusion. Therefore, it’s not surprising that
this idea appears in the tale of Kaguya-hime.
The Moon has been appreciated by the Japanese since
ancient times.
The round Earth

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