Time and the Sun For most of history, man's days and years were governed by the sun and stars. Even after clocks and watches were invented, they were set by the sun so that they read noon when the sun was at its zenith. Time is now delivered to us by the radio and television and told by the digital watch. Morning is when the alarm goes off. Summer is when you need the air conditioner. We know about satellites, galaxies, planets and black holes, but have lost touch with the logic and rhythm of sunrise, sunset, summer and winter. These things used to be understood intuitively by everybody, and their rules and special terminology were a part of the intellectual baggage of all well-educated people. Midsummer's day was celebrated at the summer solstice on June 21. Christmas is close to the Winter solstice on December 22. The vernal and autumnal equinoxes mark the beginning of Spring and Fall when the sun moves into Cancer and Capricorn, respectively. It is instructive to learn how a sundial works and watch its shadow advance through the day and vary with the seasons. In this way we can come to a better understanding of these natural phenomena and relearn the meanings of those half-understood, half forgotten names like "gnomon", "ecliptic" and "zodiac." Until the end of the 19th century, all time was local and related to the sun. Noon in Boston was not the same time as noon in New York. With the development of railroads and telegraphs widely spaced locations became linked to each other more closely in time and, there was a need to standardize time areas. In 1884 an international convention in Washington D.C. agreed on a worldwide system of time zones of 15° each. Local adjustments were allowed, as necessary, to keep political subdivisions in a single zone.