AstroMedia: The True Time Clock

AstroMedia: The True Time Clock

Time is not the same as clock time
Because the sun travels from east to west during the day as seen from the earth, it rises earlier at an eastern location and stands earlier in its midday southern position than at a western location. This local time, which is only determined by the daily course of the sun, is called True Local Time (WOZ) or True Solar Time. The west-east difference is 4 minutes per degree of longitude. In contrast, all places that lie exactly south or north of each other on the same longitude always have the same True Local Time or Solar Time. However, the sun does not move at the same speed. From 16 April to 14 June and from 2 September to 25 December, it is slightly ahead of an imaginary uniformly moving "mean sun", and slightly behind the rest of the time. As a result, the True Local Time "stretches" and "contracts" twice a year. The difference between the true local time (WOZ) and the mean local time (MOZ) derived from an imaginary "mean sun" is called the equation of time.

Conversion made easy
To convert Central European Zone Time (CET) to True Local Time with the help of the True Time Clock, only three steps are necessary:

1. set the time (CET or CEST).
2. set the geographical longitude of the desired location.
Determine the longitude of the desired location.
3. Find the desired date on the equation of time curve and set its minute line to the longitude of the location.

The true-time clock is also well suited for aligning sundials

This is what else you need for assembly

a sharp cutter knife

a good all-purpose glue

a pin

a pair of scissors