who came up with the 12 hour clock
12-hour clock The 12-hour clock can be traced back as far as Mesopotamia and Ancient Egypt.[4] Both an Egyptian sundial for daytime use[5] and an Egyptian water clock for night-time use were found in the tomb of Pharaoh Amenhotep I.[6] Dating to c. 1500 BC, these clocks divided their respective times of use into 12 hours each.
Noon Solar noon is when the Sun transits the local celestial meridian; this is when the sun is at its highest altitude in the sky, at 12 noon apparent solar time. The local or clock time of solar noon depends on the longitude and date.[1]