Keeping Time with Quasars

Keeping a standard time is an essential component of the functioning of society and daily life. It is nearly impossible to communicate, travel, land spacecraft, perform precise scientific experiments, or maintain an international economy without a consistent time that can be agreed upon by all people regardless of their region on Earth. It is taken for granted that we all experience the sun overhead at noon, sleep when it is dark, and have a reliable means of coordinating time between our respective time zones. However, the process of keeping an accurate and precise time is complex; it relies on hundreds of terrestrial and celestial factors that must be accounted for in order to produce the value known as Universal Time.