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.
Sidereal time is easy to determine with a star chart - it's equal to the right ascension that is overhead at the moment. The difference between solar and sidereal time means that the stars rise about four minutes earlier each night, or two hours earlier each month. Celestial Navigation . Before GPS systems, people used the stars for navigation. 1  Latitude, your distance north or south of the equator, is the elevation of the celestial pole above your horizon. You don't need a pole star to find latitude. 2  Longitude, your distance east and west, is harder. The key to longitude is time.