Download Documentazione sull` osservatorio astronomico di Jaipur ( India

Documentazione sull' osservatorio astronomico di Jaipur ( India) fatto costruire dal Maharajah Jai Singh II
tra il 1727 ed il 1734.
Domenica 19/07/09 partiremo per l' India. Dovremmo vederlo.
Ciao. Cieli sereni.
Franco
PS: allegati pdf esaustivi
-------------------------------------------------Jantar Mantar
In Jairpur, the capital of the federal state Rhajasthan situated in the west of India, you will find one of the
most timeless and culturally independent pieces of architecture in the world. A place of religion and science
still in its own unsecularized integrity, only comparable with the witnesses in stone of the archaic cultures.
The Jantar-Mantar (Sanskrit; translated as “Magical Device”) was built between 1728 and 1734 due to the
drafts of Maharaja Jai Singh II (1693 -1743) in the centre of Jaipur, which itself was founded 1727 as new
capital city of his principality
The Jantar-Mantar (Sanskrit; translated as “Magical Device”) was built between 1728 and 1734 due to the
drafts of Maharaja Jai Singh II (1693 -1743) in the centre of Jaipur, which itself was founded 1727 as new
capital city of his principality.
Jai Singh has designed Jaipur strictly corresponding to the architectural rules of the Shilpa Shastra, an
ancient idealistic Hindu doctrine. The city is divided into seven rectangular areas following the caste system
and preordination. In the 7th, most centered area lies the Palace, which houses the womens chambers and
the holiest sanctum. Differing from the Shilpa Shastra rules, in this holy area Jai Singh created not a temple,
but the Jantar Mantar. His capital city and observatory are, in spite of Jai Singh II's scientific and political
cosmopolitanism, of purely religious origin, a fact which is often ignored or forgotten.
materialisaton of an idea
view from the big sundial to the small sundial
in the background on the hill part of the fortress wall around Jaipur
The observatory consists of oversized stone observation devices, which get a good degree of accuracy due
to their enormous dimensions. It is the biggest of five observatories, which Jai Sing II had built. The majority
of the devices is typical for big observatories in the Islamic world. The most significant one, built by famous
Ulugh Begh (1394-1449) in Samarkand has been an inspiring example for Jai Singh. But his instruments are
unique as concerns precision, size and architectural perfection.
At least, 120 years after the invention of the telescope they still provided amazingly results.
islamic tradition
bottom left one of the twelve zodiac gnomes
in the middle the hemispheres of the Jai Praksh Yantra, top right the little sundial
Several devices, first and foremost the hemispheres of Jai Praksh Yantra set in the ground, however, are
attributed to Jai Singh as new constructions. Basically it is one marble hemisphere set in the ground about 4
metres in diameter - in itself a master piece - where above a cross with a metal ring is applied. The inside
surface is covered with coordinate lines. During the day the shadow of the metal ring allows to read the exact
position of the sun on the coordinate lines, and of course the time. During the night a simple tube was used
as a sighting device for observation.
Jai Praksh Yantra
the complementary hemispheres of Jai Praksh Yantra
behind some of the 12 zodiac gnomes used for measuring celestial coordinates
The observer lays down in the hemishere and focuses on the stars through the sighting tube, whose end is
held by the metal ring. The elongation of the tube onto the sphere's inside surface shows a star's position by
reading the coordinate lines. To simplify measurement - one person has to adjust, while the other has to hold
the tube - the Jai Praksh Yantra is made of two hemispheres, themselves complementary. In place of the
passages in one hemisphere threre are marble scales of the other and vice versa. Alternating use of the
hemispheres within a two hours change allows observation around the clock.
counterparts
you can walk on the inside of the hemispheres
in the bottom left-hand corner the centre of the scale that is half visible in the big picture
The scale's centre is located 27 degrees below the edge. The connecting line between the scale’s centre
and the metal ring points exactly to the Celestial North Pole. Proceeding from that point equatorial
coordinates of the celestial bodies can be read. The circle around the centre shows the position of the
Ecliptic Pole througout the year. It helps determining celestial coordinates, too. All those observations of the
sky are feasible just with the Jai Praksh Jantra. Maybe it is Jai Sing’s major work, particularly because it lies
in the centre of Jantar Mantar and further westward another smaller model is located.
it's own observatory
in the bottom third the centre of the scale and above the matal ring that holds the tube
on the left the inside surface of the hemisphere
Jantar Mantar
The apparent orbit of the sun around the earth - that is in fact the orbit of the earth around the sun - is called
ecliptic. It is devided into 12 equal parts named the zodiac circle. The angle of 23 degrees between the
ecliptic and the equator brings about the seasons as the variing length of day and night. On June 21 the
summer solstice is in the northern hemisphere and with it the longest day. In the southern hemisphere it is
winter solstice on June 21 with the shortest day. The sun stands vertically above 23 degrees northern
latitude (Tropic of the Cancer). On March 21 the sun stands vertically above the equator, so day and night is
identical.
astronomic fundamentals
Jantar Mantar
Eversince equinoxes are of exceptional importance for astronomers. These are the only days under
identical circumstances all over the world. Day and night are exactly of the same length. The sun rises stricly
in the east and sunset is strictly in the west. During the equinoxes both poles of the earth lie over the ecliptic
so both northern and southern hemispheres of the earth are lighted equally. In the course of the year the
northern and southern hemispheres are lighted unequally. Beyond the polar circle the day and night side is
permanently lighted for six months on each hemisphere (polar day).
equinoxes
Jantar Mantar
From the earliest period until today the vernal equinox was a reference point for position data. It can be
dertermined in a relatively easy way at any place due to the point of sunrise on the eastern horizont and the
point of sunset on the western horizont define a line straight through the oberserver's position on that day.
Prehistoric observatories (Stonehenge) are orientated towards the vernal equinox. Depending on the world
picture the vernal equinox defines a point on the horizont, on the sun's orbit or on the earth's orbit. The
peculiarities of the coordinate systems are caused by these differences in the point of view.
vernal equinox
Jantar Mantar
The easiest way to define a star's celestial position is in relation to the horizont line and the point of vernal
equinox. Due to the rotation of the earth these position data are valid only for a certain observer's location,
time and date. Observation of periodically recurring events in the sky (the sun's orbit, lunar phases, venus'
rise and set as morning and evening star, comets) allows to determine the seasons up to developping a
precise calendar, but results are fixed to a certain location. With every change of location new observation is
neccesary. This is why the horizont system cannot be used for navigation purposes.
horizont system
Jantar Mantar
A point of reference that is independent from the observer's location is offered with the Celestial Pole. All
stars seem to rotate arround it due to the earth's rotation. As the earth's axis is in circular motion itself, the
Celestial Pole rotates around the Ecliptic Pole once in about 28850 years. In the equator system the celestial
equator that is standing rectangular to the celestial pole is used as second point of reference. A star's
position is defined by its height over the equator and angle to the vernal equinox. Since the vernal equinox is
defined as a point on the celestial equator, it moves on the ecliptic as the celestial pole rotates.
equator system
Jantar Mantar
The apparent movement of the vernal equinox on the ecliptic is caused by the geocentric point of view the
equator system is based on. The rotation of the celestial pole around the ecliptic pole as seen from the earth
leads to a slow rotation of the zodiac signs around the zodiac circle. This is known since the antiquity
(Platonic Year, 25850 years). As seen from the sun, the vernal equinox is a point on the orbit of the earth.
The ecliptic system defines the position of a star in relation to the vernal equinox and the ecliptic. Within the
solar system these position data are practically absolute.
ecliptic system
Jantar Mantar
Gnomes, shadow indicators, are actually sundials. There are differences between the 14 gnomes of the
Jantar Mantar in their function, but not in principle. With a sighting stick that rests against the quadrant and
the ramp a celestial body is aimed at. At the bearing points of the sighting stick position data can be read
from engraved markings. Depending on the orientation of the ramp to a point over the horizont, to the
Celestial Pole or the Ecliptic Pole one can read position data corresponding to the horizont, equator or
ecliptic system. Additionally time can be determined from the ramp's shadow.
shadow indicators
Jantar Mantar
Over 30 metres in height, the big sundial is the most impressive and the biggest device. The ramp that
forms the indicator is orientated to the north. It's gradient of 27 degrees is equivalent to the latitude of Jaipur.
Thus the ramp points exactly to the Celestial North Pole. The shadow of the indicator falls of the wingshaped western and eastern scales. They are made of marble as the side edges of the indicator are, and
covered with delicate measuring divisions. According to the size and architectural precision, the shadow
shows the local time accurate within four minutes. Using a sighting stick accuracy lies within seconds.
Samyat Yantra
on the left the ramp over 30 metres in height
on the right the end of the eastern scale in the late afternoon
Jantar Mantar
With a sighting stick or a little shadow stick that is moved along the stairs until the shadow just touches the
edge of the quadrant, the distance in degrees of the sun or other stars from the equator can be measured.
This method allows the determination to the minute of equinoxes and solstices which are of central meaning
for all religious astronomical and astrological world systems. By the way, the ramp is sealed off from visitors.
It is still used by priests for observations. The little sundial however is open to the public. It might have been
intended for everday purpose.
on the left the end of the western scale
on the right the west side of the big sundial
Jantar Mantar
Westward from Samyat Yantra there are 12 smaller gnomes about 3 metres high that are pointing at
different directions. They are used to determining celestial coordinates. Their ramps are not orientated to the
Celestial Pole but to the Ecliptic Pole. The quadrants lie in the plane of the ecliptic. Because the Ecliptic Pole
appears to rotate around the Celestial Pole the ramp can only be oriented to the Ecliptic Pole for one fixed
date. Each of the 12 gnomes points towards the position of the Ecliptic Pole at the beginning of a zodiac
sign. With these 12 points of measurement calculation of position data for every day is possible.
zodiac gnomes
at the front some of the 12 gnomes orientated to the zodiac
in the background a detailed view of the sundial's scale made of lead inlays in marble
Among many further devices, the big astrolabe should be particularly mentioned. It is a star chart engraved
in a metal disc. Moveable rulers allow similar to a slide rule the calculation of rising and setting points as to
convert coordinates and work out horoscopes. With a sighting tube the zenith distance of a star can be
determined as well. Standard astrolabes are between 30 and 50 cm in diameter whilst the astrolabe of Jai
Singh is around two metres in diameter. Jai Singh specially developed an alloy made of seven metals that
prevents alternations in size due to warming up of the sun.
at the front a sextant as is in use for nautic navigation
in the background the northern side of the equatorial double sundial
Jantar Mantar
Unfortunately there is only a few that has been written about this uniquely integrating work of art, science
and religion, though it is used to be mentioned in special literature as extraordinary. Maybe there is no real
interest in pointing out Jantar Mantar's consequences. After all the claim to scientifc omnipotence of the
enlighted modern times is seriously relativated by Jai Singh's religious-scientific intention. Most of the
devices of the Jantar Mantar are limited to the means of a highly developed Stone Age culture. They might
as well have stood in Egypt, in South America or in Stonehenge.
Anyone who wants to know more about the Jantar Mantar should simply visit Jaipur. At the ticket office the
only literature about the Jantar Mantar I know is available, "Astronomical Observatory of Jaipur by Daulat
Singh Rajawat" and "Stone Observatories" by Prahlad Singh.
the southern side of the equatorial double sundial
in the background the top of the little sundial
----------------------------------------------------------------------------------------
Modelli 3D e Virtual Tour su:
Cieli sereni
Franco
http://www.jantarmantar.org/