Astrarium

An astrarium, also called a planetarium, is the mechanical representation of the cyclic nature of astronomical objects in one timepiece. It is an astronomical clock.

Astrario Dondi 05869 01 dia - Museo scienza e tecnologia Milano
The astrarium made by Giovanni Dondi dell'Orologio showed hour, year calendar, movement of the planets, Sun and Moon. Reconstruction, Museo Nazionale Scienza e Tecnologia Leonardo da Vinci, Milan.

History

Greek and Roman World

NAMA Machine d'Anticythère 1
The Antikythera mechanism (main fragment)

The first astraria were mechanical devices. Archimedes is said to have used a primitive version that could predict the positions of the Sun, the Moon, and the planets. On May 17, 1902, an archaeologist named Valerios Stais discovered that a lump of oxidated material, which had been recovered from a shipwreck near Antikythera, held within it a mechanism with cogwheels. This mechanism, known as the Antikythera mechanism, was recently redated to end of the 2nd century BCE.[1] Extensive study of the fragments, using X-rays, has revealed enough details (gears, pinions, crank) to enable researchers to build partial replicas of the original device.[2][3][4] Engraved on the major gears are the names of the planets, which leaves little doubt as to the intended use of the mechanism.

By the end of the Roman Empire, the know-how and science behind this piece of clockwork was lost.

Middle Ages and Renaissance

The first modern documented astrarium clock was completed in 1364 by Giovanni de' Dondi (1318–1388), a scholar and physician of the Middle Ages interested in astronomy and horology. The original clock, consisting of 107 wheels and pinions, has been lost, perhaps during the sacking of Mantua in 1630, but de' Dondi left detailed descriptions which have survived, enabling a reconstruction of the clock. It displays the mean time, sidereal, (or star), time and the motions of the sun, moon and the five then-known planets Venus, Mars, Saturn, Mercury, and Jupiter. It was conceived according to a Ptolemaic conception of the solar system. De' Dondi was inspired by his father Jacopo who designed the astronomical clock in the Piazzi dei Signori, Padua, in 1344 – one of the first of its type.

In later ages more astraria were built. A famous example is the one built in 1774 by Eise Eisinga from Dronrijp, Friesland, the Netherlands. It displayed all the planets and was fixed to the ceiling in a house in Franeker where it can still be visited.

In modern times, the astrarium has grown into a tourist attraction as a commercially exploited planetarium-showing in IMAX theaters. With such presentations as 'The history of the Universe', as well as other astronomical phenomena.

See also

References

  1. ^ "Antikythera Mechanism Research Project". www.antikythera-mechanism.gr. Archived from the original on 2012-09-26. Retrieved 2008-03-17.
  2. ^ "Solid Models of the Antikythera Mechanism | Antikythera Mechanism Research Project". www.antikythera-mechanism.gr.
  3. ^ "Archived copy". Archived from the original on 2006-12-06. Retrieved 2006-11-29.CS1 maint: Archived copy as title (link)
  4. ^ "Archived copy". Archived from the original on 2008-02-16. Retrieved 2006-11-29.CS1 maint: Archived copy as title (link)

Literature

  • Giovanni Dondi dell'Orologio – "Tractatus astarii"

External links

Astrarium of Giovanni Dondi dell'Orologio

The Astrarium of Giovanni Dondi dell'Orologio was a complex astronomical clock built between 1348 and 1364 in Padova, Italy, by the doctor and clock-maker Giovanni Dondi dell'Orologio. The Astrarium had seven faces and 107 moving parts; it showed the positions of the sun, the moon and the five planets then known, as well as religious feast days. It was one of the first mechanical clocks to be built in Europe.

BPL (time service)

BPL is the call sign of the official long-wave time signal service of the People's Republic of China, operated by the Chinese Academy of Sciences, broadcasting on 100 kHz from CAS's National Time Service Center in Pucheng County, Shaanxi at 34°56′54″N 109°32′34″E, roughly 70 km northeast of Lintong, along with NTSC's short-wave time signal BPM on 2.5, 5.0, 10.0, and 15.0 MHz.

BPL broadcasts LORAN-C compatible format signal from 5:30 to 13:30 UTC, using an 800 kW transmitter covering a radius up to 3000 km.

Chronometry

Chronometry (from Greek χρόνος chronos, "time" and μέτρον metron, "measure") is the science of the measurement of time, or timekeeping. Chronometry applies to electronic devices, while horology refers to mechanical devices.

It should not to be confused with chronology, the science of locating events in time, which often relies upon it.

Common year

A common year is a calendar year with 365 days, as distinguished from a leap year, which has 366. More generally, a common year is one without intercalation. The Gregorian calendar, (like the earlier Julian calendar), employs both common years and leap years to keep the calendar aligned with the tropical year, which does not contain an exact number of days.

The common year of 365 days has 52 weeks and one day, hence a common year always begins and ends on the same day of the week (for example, January 1 and December 31 fell on a Sunday in 2017) and the year following a common year will start on the subsequent day of the week. In common years, February has four weeks, so March will begin on the same day of the week. November will also begin on this day.

In the Gregorian calendar, 303 of every 400 years are common years. By comparison, in the Julian calendar, 300 out of every 400 years are common years, and in the Revised Julian calendar (used by Greece) 682 out of every 900 years are common years.

Giovanni Dondi dell'Orologio

Giovanni Dondi dell'Orologio (c. 1330 – 1388), also known as Giovanni de' Dondi, was an Italian physician, astronomer and mechanical engineer in Padua, now in Italy. He is remembered today as a pioneer in the art of clock design and construction. The Astrarium, which he designed and built over a period of 16 years, was a highly complex astronomical clock and planetarium, constructed only 60 or so years after the very first mechanical clocks had been built in Europe, and demonstrated an ambitious attempt to describe and model the planetary system with mathematical precision and technological sophistication.

HD2IOA

HD2IOA is the callsign of a time signal radio station operated by the Navy of Ecuador. The station is located at Guayaquil, Ecuador and transmits in the HF band on 3.81 and 7.6 MHz.The transmission is in AM mode with only the lower sideband (part of the time H3E and the rest H2B/H2D) and consists of 780 Hz tone pulses repeated every ten seconds and voice announcements in Spanish.

While sometimes this station is described as defunct, reception reports of this station on 3.81 MHz appear regularly at the Utility DX Forum.

Intercalation (timekeeping)

Intercalation or embolism in timekeeping is the insertion of a leap day, week, or month into some calendar years to make the calendar follow the seasons or moon phases. Lunisolar calendars may require intercalations of both days and months.

List of astronomical instruments

Astronomical instruments include:

Alidade

Armillary sphere

Astrarium

Astrolabe

Astronomical clock

the Antikythera mechanism, an astronomical clock

Blink comparator

Bolometer

the Canterbury Astrolabe Quadrant

Celestial sphere

Charge-coupled device

CMOS sensor

Coronagraph

Cosmolabe

Dioptra

Equatorial ring

Equatorium

Gnomon

Interferometer

Meridian circle

Microchannel plate detector

Mural instrument

the Nebra sky disk

Nocturnal

Octant (instrument)

Optical spetrometer, a.k.a., Spectrograph

Orrery

Photographic plate

Photometer

Planisphere

the Prague astronomical clock

Quadrant (instrument)

Reticle

Skaphe

Sextant

Starshade

Telescope

Torquetum

Triquetrum (astronomy)

Zenith telescope

Minute

The minute is a unit of time or angle. As a unit of time, the minute is most of times equal to ​1⁄60 (the first sexagesimal fraction) of an hour, or 60 seconds. In the UTC time standard, a minute on rare occasions has 61 seconds, a consequence of leap seconds (there is a provision to insert a negative leap second, which would result in a 59-second minute, but this has never happened in more than 40 years under this system). As a unit of angle, the minute of arc is equal to ​1⁄60 of a degree, or 60 seconds (of arc). Although not an SI unit for either time or angle, the minute is accepted for use with SI units for both. The SI symbols for minute or minutes are min for time measurement, and the prime symbol after a number, e.g. 5′, for angle measurement. The prime is also sometimes used informally to denote minutes of time.

OLB5

OLB5 was the callsign of a Czech time signal radio station. The station was located at Poděbrady and transmitted time signals which originated from the OMA (time signal) clock at Liblice.

The station transmitted in the HF band, on 3.17 MHz with 1 kW.

Orrery

An orrery is a mechanical model of the Solar System that illustrates or predicts the relative positions and motions of the planets and moons, usually according to the heliocentric model. It may also represent the relative sizes of these bodies; but since accurate scaling is often not practical due to the actual large ratio differences, a subdued approximation may be used instead. Though the Greeks had working planetaria, the first orrery that was a planetarium of the modern era was produced in 1704, and one was presented to Charles Boyle, 4th Earl of Orrery – whence the name. They are typically driven by a clockwork mechanism with a globe representing the Sun at the centre, and with a planet at the end of each of the arms.

Solar time

Solar time is a calculation of the passage of time based on the position of the Sun in the sky. The fundamental unit of solar time is the day. Two types of solar time are apparent solar time (sundial time) and mean solar time (clock time).

Tempus fugit

Tempus fugit is a Latin phrase, usually translated into English as "time flies". The expression comes from line 284 of book 3 of Virgil's Georgics, where it appears as fugit inreparabile tempus: "it escapes, irretrievable time". The phrase is used in both its Latin and English forms as a proverb that "time's a-wasting". Tempus fugit, however, is typically employed as an admonition against sloth and procrastination (cf. carpe diem) rather than a motto in favor of licentiousness (cf. "gather ye rosebuds while ye may"); the English form is often merely descriptive: "time flies like the wind", "time flies when you're having fun".

The phrase's full appearance in the Georgics is:

The phrase is a common motto, particularly on sundials and clocks.

Term (time)

A term is a period of duration, time or occurrence, in relation to an event. To differentiate an interval or duration, common phrases are used to distinguish the observance of length are near-term or short-term, medium-term or mid-term and long-term.

It is also used as part of a calendar year, especially one of the three parts of an academic term and working year in the United Kingdom: Michaelmas term, Hilary term / Lent term or Trinity term / Easter term, the equivalent to the American semester. In America there is a midterm election held in the middle of the four-year presidential term, there are also academic midterm exams.

In economics, it is the period required for economic agents to reallocate resources, and generally reestablish equilibrium. The actual length of this period, usually numbered in years or decades, varies widely depending on circumstantial context. During the long term, all factors are variable.

In finance or financial operations of borrowing and investing, what is considered long-term is usually above 3 years, with medium-term usually between 1 and 3 years and short-term usually under 1 year. It is also used in some countries to indicate a fixed term investment such as a term deposit.

In law, the term of a contract is the duration for which it is to remain in effect (not to be confused with the meaning of "term" that denotes any provision of a contract). A fixed-term contract is one concluded for a pre-defined time, although it may also include provision for it to be extended. A contractor required to deliver against a term contract is often referred to as a "term contractor".

The Red Sea Astrarium

The Red Sea Astrarium (TRSA) is an integrated resort destination on the shores of the Red Sea. It is considered the first themed entertainment attraction at the coastal city of Aqaba, Jordan, and the first to use green energy to minimize adverse environmental impacts.

The key attractions include dining, retail, nightlife, rides, shows, museum exhibits, theme parks, water parks, interactive walk-throughs, and a ‘Star Trek Experience’ based upon the new Star Trek franchise.

The resort was designed by Rubicon Group Holding (RGH). The resort is under implementation and projected to open in 2017.

Tomorrow (time)

Tomorrow is a temporal construct of the relative future; literally of the day after the current day (today), or figuratively of future periods or times. Tomorrow is usually considered just beyond the present and counter to yesterday. It is important in time perception because it is the first direction the arrow of time takes humans on Earth.

Uhrenmuseum Beyer

The Uhrenmuseum Beyer (Beyer Watch and Clock Museum) is located in the heart of the city of Zürich, Switzerland and is one of the world's leading private museums dedicated to horology.

The museum is located on the lower level of Bahnhofstrasse 31, the main shopping boulevard. It is affiliated with Chronometrie Beyer, a high grade watch retailer run by the same family for generations.

The core of the museum was acquired during the life of Theodore 'Teddy' Beyer, a pioneer in collecting antique timekeepers. The collection is made up of premechanical timekeepers (sundials, sandglasses, water and fire clocks) as well as clocks and watches from around the world and covering all eras.

The collection is particularly strong regarding early clocks and watches, including several pieces from the gothic and renaissance era, as well as complicated pieces with many complications.

Many of the displayed pieces are unique and/or significant in the history of watchmaking, and therefore are often loaned out to major museums around the world. The collection includes one of the early marine chronometers by Ferdinand Berthoud, a pendule sympathique by Breguet, a pocket watch with astronomical indications by Auch, several bespoke late 20th century watches by George Daniels, one of the few reproductions of the astrarium by De Dondi to name just a few highlights. Furthermore, there are superb Geneva made enameled pocket watches, and a most instructive timeline illustrating the history of the Neuchâtel pendule.

Additionally there is a good small display of locally made clocks and watches including such Zurich makers as Bachoffner, Liechti and Ochsner.

YVTO

YVTO is the callsign of the official time signal from the Juan Manuel Cagigal Naval Observatory in Caracas, Venezuela. The content of YVTO's signal, which is a continuous 1 kW amplitude modulated carrier wave at 5.000 MHz, is much simpler than that broadcast by some of the other time signal stations around the world, such as WWV.

The methods of time transmission from YVTO are very limited. The broadcast employs no form of digital time code. The time of day is given in Venezuelan Standard Time (VET), and is only sent using Spanish language voice announcements. YVTO also transmits 100 ms-long beeps of 1000 Hz every second, except for thirty seconds past the minute. The top of the minute is marked by a 0.5 second 800 Hz tone.The station previously broadcast on 6,100 MHz but appears to have changed to the current frequency by 1990.

Yesterday (time)

Yesterday is a temporal construct of the relative past; literally of the day before the current day (today), or figuratively of earlier periods or times, often but not always within living memory.

Key concepts
Measurement and
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Philosophy of time
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