Welcome to the website of the
Torreón Jardín Analemmatic sundial
(Torreón, Coahuila, México)

The living sundial

An enthusiastic group of people from the Torreón Jardín area has set out to construct a unique, colorful sundial here. It consists of an oval ring, 6 meters wide, along which the hours are indicated. In the center is a date scale. Step on this scale on today's date, and you yourself become part of this celestial clock: your shadow will point to the right time. No watch needed anymore!

Click the thumbnails below for an enlarged view and more details.

Sundial design

Geographic location: Latitude 25°31' N, Longitude 103°25' W

The dial face depicts day and night. The sun rays refer to the local climate. The central ray points to the north. The dial face darkens towards the south, representing the twilight followed by the night. The latter is decorated with the moon and some stars.

The sundial has been made from different types of stone, almost all from the surrounding area, such as white and red marble, travertine, yellow and black flagstone, limestone, etc.

The finished dial has been set in desert plants, native to the region.

The sundial includes several elements:

Date scale

Equinoctial line	Meridian line	Correction values

The date scale provides correction values to convert solar time to legal time.

Example
June 10th: the correction for this day it is not provided on the scale, so we should interpolate it from the neighboring values; the correction is about 53 minutes.

If the sundial indicates 10:00 a. m.:
  a)   plus 53 minutes, this gives 10:53 hr,
  b)   plus 1 hour of summer time, which makes it 11:53 hr,
and this should be the time indicated by your watch. (If not, get yourself a new watch.)

Terminator maps

Six disk-shaped maps at the east and west sides show the course of the terminator (the border between day and night) across the Mexican Republic on astronomically important dates.

The three maps at the west side show:

• The terminator line at sunrise at the summer solstice (5:12 a.m.)
• The terminator line at sunrise at the winter solstice (6:47 a.m.)
• The terminator line at sunrise at the equinox (6:00 a.m.).

The three maps at the east side show the terminator line at sunset at the same dates (6:47 p.m., 5:12 p.m. and 6:00 p.m., respectively).

Wind rose or nautical rose

The motto Captivum Motus, which means "Motion [of the Sun] captured" is placed above the wind rose.

Information that can be obtained from this sundial:

1. Solar time

2. Correction values to convert solar time to legal time

3. Solstices and equinox sunrise and sunset times

4. The terminator line across the Mexican Republic as seen from space at sunrise and sunset at solstices and equinox

5. The cardinal points of the compass

6. Watching the shadow makes it easy to understand the movement of the earth with respect to the sun throughout the day and the year

7. Other geographic information, such as the local latitude and longitude, solar declination and azimuth, etc.

An information panel explaining the various aspects of this sundial is present at the site. The picture explaining the analemmatic dial by the projection of an equatorial dial was taken from this webpage of Frans Maes.

• Read about the history of the project

• Read about other sundials in Torreón

For more information about this sundial, write to: Martha A. Villegas

We gratefully appreciate the help of Frans Maes with this project, including the creation of this page. If you would like to know more about different sundial types in many places of the world, visit Frans Maes' Sundial site.

More information about sundials:

• North American Sundial Society

• British Sundial Society

• Sundials on the Internet

• Carpe Diem. El mundo de los relojes de Sol

• Relojes de Sol de Murcia, España

More information about the Torréon area:

• La Laguna