Geography Reference
In-Depth Information
through the Royal Greenwich Observatory, which is in the London suburb of Greenwich, as well as
parts of Europe, Africa, and the Atlantic Ocean. The British system was chosen largely because in
1884 Britain was the world's major military and economic power, and also had a fine tradition of
mapmaking.
Getting Lined Up
With the starting lines in place, one can now contemplate putting all of the other lines of latitude and
longitude on a globe. In doing that, Hipparchus used the notion that 360 degrees (°) are in a circle.
Accordingly, he drew lines of latitude such that each and every one is separated by one degree of arc
from the next. He then did the same with longitude. This is why lines of latitude and longitude are
referred to as degrees.
Why is Earth 360° round?
The ancient Sumerians believed there were 360 days in a year. Like other civilizations
way back when, the Sumerians equated their gods with celestial objects. Not surprisingly,
the sun god was especially important. Because it took the Earth 360 days to travel around
the sun (or so they believed), the Sumerians figured the number 360 had extra-special
significance. As a result, they developed a system of mathematics based on multiples
of 6 and 60. Nowadays, we would call it
base-6 mathematics
or (get ready for this) a
sexagesimal
system. In any event, 6 × 60 = 360.
The ancient Egyptians adopted the ancient Sumerians' numerical ideas, and eventually
discovered the error concerning the length of the year. But by then, however, the number
360 had achieved such acceptance and status that the Egyptians decided not to mess
with it. Accordingly, they kept the 360-day year but, being fun-loving people, added an
annual 5-day holiday.
The ancient Greeks, like the ancient Egyptians, were adept at adopting things and ideas
from civilizations more ancient than they. So when Hipparchus, in about 140 B.C., began
fiddling with the notion of dividing a circle (and Earth) into degrees, he chose the number
360.
