JANTAR MANTAR                           

Hi everyone sorry because could not write blog for you all I have a favourite hobbie that is to write down about our most precious UNIVERSE. Jantar Mantar a place in Jaipur,India is one of ancient place where astronomers can research about our space. It has a collection of nineteen architectural astronomical instruments, built by the Rajput king Sawai Jai Singh II, and completed in 1734 CE. It features the world's largest stone sundial, and is a UNESCO World Heritage site.Now lets see about its astronomical instruments -

☺Rama Yantra-

The Rama Yantra consists of a pair of cylindrical structures, open to the sky, each with a pillar or pole at the center. The pillar/post and walls are of equal height, which is also equal to the radius of the structure. The floor and interior surface of the walls are inscribed with scales indicating angle of altitude and azimuth. Rama Yantras were constructed at the Jaipur and Delhi observatories only.The Rama Yantra is used to observe the position of any celestial object by aligning an object in the sky with both the top of the central pillar, and the point on the floor or wall that completes the alignment. In the daytime, the sun’s position is directly observed at the point where the shadow of the top of the pillar falls on the floor or wall. At night, an observer aligns the star or planet with the top of the pillar and interpolates the point on floor or wall that completes the alignment through the use of a sighting guide.

The floor is constructed as a raised platform at chest height, and is arranged in multiple sectors with open spaces between them. This provides a space for the observer to move about and comfortably sight upwards from the inscribed surface. The instrument is most accurate near the intersection of floor and wall, corresponding to an altitude of 45 degrees. Here, the markings are at their widest spacing, and give an accuracy of +/- 1’ of arc. For altitude readings greater than 45 degrees, the accuracy diminishes, and diminishes to +/- 1 degree near the base of the pillar.

     ☺Chakra yantra

The Chakra Yantra is the pair of upright metal circles in the photo. They stand between a pair of hemispheres (bowl shapes) lowered into the ground in front of and behind the metal circles. 

As for the Chakra Yantra, it is an instrument for finding the right ascension and declination of a planet or other celestial body observed at night.

To understand these coordinates, it may help if you visualize the earth's lines of longitude and latitude projected up onto the sky, such that the north star corresponds to earth's north pole. Earthly latitude is the angular distance north or south of the equator, and earthly longitude is the angular distance around the polar axis as measured from any arbitrary starting point - in this case, the meridian of Jaipur.

The projection into the heavens of earth's latitude lines is called the "declination", and the projection of earth's longitude lines is called the "right ascension". (See Basic Celestial Phenomena for more information about this.)

Now say you want to locate a planet in the sky. You do that the same way you would locate a spot on earth, by moving down from the north pole to the correct latitude and then moving around that circle of latitude until you reach the correct longitude. When you do this on the celestial sphere instead of the earthly one, you get the celestial coordinates of declination and right ascension.

The Chakra Yantra lets you measure these coordinates. The axis of the metal circle (I will discuss only one of the pair; the other is, apparently, the same) is perpendicular to the crossbar (notice where the axis is attached to the upright posts). The axis points towards the north pole, and the circle pivots around this axis. In the middle of the circle is a hole for attaching a sighting tube, which pivots around the circumference of the circle. (You don't see a sighting tube in the photo, because one is not currently attached to the instrument, so just pretend that it's there.)

To find a planet, imagine that the whole contraption, circle and sighting tube, is aimed at the north star (perpendicular to the crossbar), and that the planet is (let's say) 10 degrees below and 20 degrees to the right of the north star. Imagine how you have to move the sighting tube to see the planet. First of all, you pivot the sighting tube 10 degrees down the metal circle. This is the declination, 10 degrees below north, marked as such on the circle. Then you have to pivot the metal circle 20 degrees counterclockwise around its axis