Time zones are needed because Earth makes a complete rotation every 24 hours (i.e. travelling
every 15 degrees east or west to a place is equivalent to an hour time difference) Therefore;
each 15-degree longitude band is assigned a standard time zone in reference to the prime
meridian (Greenwich Mean Time- by international agreement) as the master reference time for
all points on Earth.
-This way noon occurs in every time zone while the sun is at its highest point in the sky each day