Sundials and Astronomical Clocks
Una ex his erit tibi ultima.
One of these [hours] will be your last.
—Unknown
Astrotourism is a much greater field of exploration than viewing the night sky. Traveling to watch rocket launches or reentries is included in the current definition of this new segment of tourism, but that was not always the case. Astronomical tourism began in the 1940s and has expanded upon its definition as markets and technology advanced.
Places like Space Camp in Alabama, space-themed hotels, museums of astronomy weightlessness experiences, astronaut boot camps are being included as possible interests of the astrotourist. As science’s pursuit of knowledge in the emerging fields of astrophysics, aerospace engineering, astrometry, astrogeology, cosmology, astrobiology, and archeoastronomy develop and expand, so will the possible opportunities for the astrotourist to consume.
Food tourism is well established and is augmented by the recent ascent of agritourism. Agritourism expands upon food tourism by bringing travelers to the source and providing options to participate in food production, harvesting, and working on a farm or ranch. Humanity’s relationship with, and response to what transpires in the sky, can be part of the astrotourist’s exploration.
We have measured the stars’ movements for thousands of years, and the devices that track the motion of the heavens continue to advance as technology evolves. In the 14th century, time-keeping mechanisms were designed to measure the turn of the celestial wheel and did so with astounding accuracy. These astronomical clocks are still working—and in some places, the town’s biggest attraction.
Sundials
A distinction made in this text designates a sundial as a “star clock.” The nearest star, our sun, and Earth’s position with it are used to tell time. Sundials are the earliest type of time-keeping devices. Time is determined using the sun’s rays to create a shadow with an object (i.e., a stick) and track the shadow’s path throughout the day. The oldest known sundial was found in Egypt and dates from Thutmose III, about 1,500 years BC. It held two segments of stone: one that held the needle and another marked to indicate the hours of the day.1
As the day progresses and the earth turns, the sun appears to travel across the sky, which causes an object’s shadow to move; this is interpreted as the passage of time. The first object for indicating the time of day was probably the gnomon (Greek for “he who knows”), dating from about 3500 BC. For over 5,000 years, sundials (star clocks) were the standard for telling time. Until the 19th century, sundials were still used to reset mechanical clocks.2 Using a star to tell time was so accurate, the entire population of a city set their watches to it.
We may here remark that at Paris, and we also believe at Edinburgh (during the 18th and 19th century) and elsewhere, the hour of noon was at one time proclaimed by a cannon, which was fired by the rays of the sun concentrated on a magnifying glass so placed as to ignite the powder in the touch-hole when the sun reached its meridian height. The gun stood on a platform which was marked as a sundial, and therefore, simultaneously with the explosion, the gnomon cast its shadow on figure XII.3
As clocks came into fashion and technology advanced, the dial-makers were less in demand; it seemed as though they were destined to go the way of the muzzle-loading rifle. In 1872, Margaret Gatty, author of The Book of Sundials, wrote, “In spite, however, of the decay and destruction of older examples, the day of the sundial is not yet done. Many new ones have been set up within the last few years. Horizontal dials are still erected in gardens with their graceful pedestals, vertical ones on country houses, and occasionally on a school or public building.” Today, 148 years later, there are original and impressive sundials that would have delighted Mrs. Gatty, as they are dramatic and noble installations located in city centers, on college campuses, in front of museums, and municipal parks.
The activities of the astrotourist should not be confined to what only happens at night, as the night is but a shadow cast by earth, giving us the darkness to see the stars. During the day, Sol shines too brightly for us to see other stars, but we can track the shadow cast by ingenious devices that not only tell the time of day but mark the solstices and equinoxes.
Some of these timekeepers go well beyond simple dials and venture into the realm of inspired and wondrous. In some countries, they are considered bona fide tourist attractions that would fall into the purse and the purveyor of astrotourism. Star clocks and sundials are an exemplary addition to any destination you create or manage. There is a wide assortment of dials that can be integrated, each with its own charm and characteristics.
• Horizontal dials
• Vertical dials
• Equatorial dials
• Polar dials
• Analemmatic dials
• Reflected ceiling dials
• Portable dials
The Sundial Bridge at Turtle Bay in Redding, California (1999 CE), has ultramodern elements, as it functions as both a cantilever bridge and a sundial. A towering edifice (66m) is located at one end, holding up the bridge and acting as the gnomon. The tower’s shadow is cast upon a large dial to the north of the bridge, laid out on the ground; however, it is accurate only one day a year—the solstice. The tip of the shadow moves at approximately one foot per minute, providing the spectator the opportunity to meditate and reflect upon our spinning planet.4
Jantar Mantar (1724 CE), located in Delhi, India, is a popular destination with several various astronomical instruments, including the Samrat Yantra (Supreme Instrument), an equinoctial sundial of enormous proportions. It measures 90 feet high, and its shadow marks the time of day with extreme precision as it is capable of measuring time to an accuracy of two seconds. It remains one of the most popular tourist attractions in India. A small cupola on top is used for announcing eclipses and forecasting monsoons.5
Figure 9.1 Sundial Bridge, Turtle Bay photo
Source: VisitRedding.com
One of the most visited places in the world is a sundial, the obelisk in Vatican City. This 25.5 m tall stone monolith acts as the gnomon for a sundial laid out on the pavement. This Egyptian obelisk was brought to Rome by Emperor Caligula in 37 AD and stood in its original spot, the Circus of Caligula, until 1586, when it was moved to the center of St. Peter’s Square.6 In 1817, the pavement of St. Peter’s Square was inlaid with a compass rose and a sundial. The shadow cast marks the sun’s movements at midday on the zodiac signs, and two inlaid discs act as markers for the winter and summer solstices.7
Astronomical Clocks
Another consideration for inclusion into the field of astrotourism is the astronomical clock. These highly visited landmarks hold all of the enchantment and whimsy of a toy maker’s most eccentric contraption while being a precise technological device. When these mechanical curiosities began to appear in the 15th century, they were state-of-the-art; to this day, they command the attention of even the most jaundiced tourists. Along with telling the hour and minute of the day, these clocks correspond to the sun’s movement as it passes through the zodiac, the planets, the phases of the moon, or the sky visible at a given time.7
Astronomical clocks are mostly found in city centers, and centuries later, they remain one of the most visited and highly rated attractions. The astrotourist will see these landmarks with a nuanced and discerning eye, having a deeper understanding of what these clocks are measuring and tracking. They will inspire most every traveler, even as they carry a smartphone capable of extraordinary computing power. Though the Renaissance was still centuries away, astronomical clocks represented some of the most advanced technology of the day, spellbinding and mystifying the common man.
A sky as pure as water bathed the stars and brought them out.
—Antoine de Saint-Exupéry (poet/aviator)
Besançon, France (1860)
The Besançon Cathedral Clock is one of the world’s most complex timepieces. The clock features 30,000 pieces, 70 dials, and 122 indicators. It tells the local time in 17 places around the world, times of sunrise and sunset, the time and height of the tides in eight French ports, has a perpetual calendar with leap year cycles, plus an orrery (mechanical model of the universe), and 21 automata. Clockmaker Auguste-Lucien Vérité constructed it, and over a century and a half later, it still is in working order. The clock is said to register up to 10,000 years (a claim that has yet to be proven), including adjustments for leap year cycles.8
Prague, Czech Republic (1410)
The Prague Orloj is the world’s oldest working astronomical clock of its kind. It is located in the Old Town City Hall. A medieval clock that features an astronomical dial, “The Walk of the Apostles,” features an hourly show of moving sculptures and a monthly calendar dial with the 12 signs of the zodiac. The clock is the center of Prague and it is still the city’s most popular tourist attraction six centuries later.9
Lund, Sweden (1387)
This monumental timepiece, the Horologium Mirabile, contains exact and modern pieces of engineering. The Lund Cathedral was built in the mid-12th century, but the elegant astronomical clock was not installed until 1387. By calculating the moon’s precise movements, this timepiece could determine the dates on which religious holidays would occur. The astronomical inner workings of the clock were updated to be accurate from 1923 to 2123.10
Figure 9.2 The Horologium Mirabile
Photo: Melissa Isla Venegas
Somerset, England, (circa 1386–1392)
The famous Wells Cathedral clock is considered to be the second oldest clock mechanism in Britain. The face is inside the church and displays the sun and moon’s movements, the moon phases, and the time elapsed since the last new moon. It is crafted in the pre-Copernican model of the universe, where the earth is at the solar system center. Small automatons come to life on the quarter-hour, one of which (Jack Blandifer) strikes two bells with his hammers and heels. Concurrently, jousting knights appear above the clock face, while two striking jacks (in the form of knights in armor) appear on the outer face.11
Rouen, Normandy, France (1389)
The Gros-Horloge clockworks date from 1389, but the face and its current location date to the 16th century. The Renaissance facade is represented by a golden sun with 24 rays on a starry blue background. On the upper part of the dial, a recessed moon turns, revealing its phases; it completes a full rotation in 29 days. The weekdays are represented by Roman gods in an opening at the base of the dial.12
Figure 9.3 Zytglogge Tower Clock
Source: Copyright Bern Welcome
The Zytglogge tower holds a 15th-century astronomical clock that powers an hourly performance incorporating a dancing jester, parading bears, and a gilded figure, Chronos; he flips an hourglass and opens his mouth to swallow with each strike of the bell. The dial of the Zytglogge’s astronomical clock is built in an astrolabe and has two faces, one on top of the other. It is divided into three zones: the black night sky, the deep blue zone of dawn, and the light blue day sky. A moon dial, displaying its phase, circles the zodiac’s inner ring and features two suns. The smaller one indicates the date on the calendar dial, and the larger one circles the zodiac, with one revolution per year.13
Venice, Italy (1496–1499)
St. Mark’s Clock on the Piazza San Marco displays the time, the moon phase, and the sun’s current location in one of the 12 Zodiac signs. The clock tower is topped by two bronze figures that strike a bell hourly.14 Twice a year, on the sixth of January (Epiphany) and the Thursday that occurs 40 days after Easter (Ascension Day), automatons behind the clock animate and make an appearance. Led by an angel with a trumpet, the three mechanical Magi pass before the Virgin and Child and disappear.15
Cremona, Italy (1583–1588)
The resplendent astronomical clock in the Torrazzo bell tower is the largest in the world and is a true masterpiece of engineering. The face is the sky, replete with zodiac constellations through which the sun and moon move. The hands denote the hours, the lunar phases, the months, the constellations, and the zodiac signs. Another hand completes a full circle every 18 years and three months (the Metonic cycle); when the sun and the moon hands are superimposed, it means that an eclipse is taking place.16
Lier, Belgium (1930)
The Zimmer tower was built in the 14th century, but the clockwork inside was made in the 20th century. The dial face consists of 12 different clocks encircling a central one. The encircling clocks indicate time on all continents, phases of the moon, tidal movement, Metonic cycle, solar cycle, lunar cycle, and zodiac signs. Unlike any other astronomical clock, it tracks the earth’s wobble process, which cycles over 25,800 years; unsurprisingly, it holds the world’s record for the slowest clock pointer. At each quarter-hour, automatons come to life that depicts three phases of life: child, adolescent, and adult; when the hour strikes, an old man appears, joining the other three. The noon hour (like most clocks) displays the biggest pageant, which consists of a celebratory parade of kings, mayors, and burgomasters from the last 100 years.17
Figure 9.4 Torrazo Bell Tower Clock
Image: @fotografarechepassione