They
created simple sundials (clocks) called shadow sticks.
2,000 years ago, scientists discovered that if the shadow
stick was slanted, it kept more accurate time than a straight
object. They learned that if the stick (called a gnomon)
was slanted to the same degree as the latitude where it is
placed, it kept accurate time all year long. (This is because
the earth's axis is also tilted.)
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