Rivers were used to turn watermills and the Romans even used geothermal water for heating. Until the middle of the 18th century renewable sources of energy were the only forms of energy available, but then, with the advent of the Industrial Revolution, fossil fuels began to be exploited.
The Sidereal Zodiac is the position of the sun referenced against the star background, as a measure of the flow of time. The framework for the star background is the constellations the sun passes in front of. This is the one astronomers use.
So, the sidereal rotation period is the TRUE ROTATION PERIOD of a celestial body. As in how much time elapses from when any distant star of interest rises to when same distant star rises again. It was later confirmed by inertial measurements, that without even looking outside Earth's atmosphere, we could measure its true rotation period.