Humanism in the age of Henry VIII. London ; Dover, N.H. : Croom Helm, 1986 (OCoLC)795302915: Named Person: Henry, King of England; Henry, King of England; Henry, King of England: Document Type: Book: All Authors / Contributors: Maria Dowling
Prior to 1972, this time was called Greenwich Mean Time (GMT) but is now referred to as Coordinated Universal Time or Universal Time Coordinated (UTC). It is a coordinated time scale, maintained by the Bureau International des Poids et Mesures (BIPM). It is also known as Z time or Zulu Time.
Two components are used to determine UTC: 1  International Atomic Time (TAI): A time scale that combines the output of some 400 highly precise atomic clocks worldwide, and provides the exact speed for our clocks to tick.  Universal Time (UT1), also known as astronomical time or solar time, refers to the Earth's rotation.