For most of human history, we kept time by Earth’s place in space. The second was a subdivision of an Earth day, and, later, an Earth year: The timespan was defined by where Earth was. Then came the atomic clock.
University Communications
For most of human history, we kept time by Earth’s place in space. The second was a subdivision of an Earth day, and, later, an Earth year: The timespan was defined by where Earth was. Then came the atomic clock.