CM Dr. Yadav Becomes Teacher
Observed zero shadow in shadow operation system on the Shanku Yantra and explained solar motion to all present Shadow disappeared at Dongla Observatory at 12:28 PM on Saturday
prativad 
Chief Minister Dr. Mohan Yadav observed the rare astronomical phenomenon that occurs on 21st June at the Varahamihira Astronomical Observatory located in Dongla. Chief Minister Dr. Yadav observed the zero shadow phenomenon in the shadow operation system on the Shanku Yantra and explained to all present the concept of time variation and calendar calculation through solar movement. Acting as a teacher, he explained astronomical science based on the Indian knowledge tradition to the dignitaries and public representatives present.
On this occasion, In-charge Minister Shri Gautam Tetwal, MP Shri Anil Firojiya, Public representatives Shri Rajesh Dhakad, Shri Bahadur Singh Chauhan, Chief Secretary of Science and Technology Shri Sanjay Dubey, Director General of the Madhya Pradesh Council of Science and Technology Dr. Anil Kothari, Additional Shri Shivkumar Sharma and students were present.
Shanku Yantra
In the centre of this platform constructed on horizontal circle of the horizon, a conical structure (Shanku) is installed, by whose shadow the speed of the Sun is measured. On this circular platform, three lines are drawn, which represent different positions of the Sun during the Uttarayan (northern solstice) and Dakshinayan (southern solstice). When the Sun reaches the last point of Uttarayan (Rajun), a special astronomical phenomenon occurs in Dongla. At 12:28 PM, the shadow of the cone disappears.
This event proves that the Sun’s northern extreme declination (23°26') and the latitude of Dongla are the same. On this day (Rajun), the duration of the day is the longest. Thereafter, the Sun begins its movement towards Dakshinayan, and the duration of the day gradually decreases. In this sequence, when the Sun is on the equator (23rd September), day and night become equal. When the Sun reaches the final point of Dakshinayan (Tropic of Capricorn), the shadow of the Shanku on this instrument becomes the longest and the day length is the shortest (22nd December). Again, from the next day, Uttarayan begins and the day length gradually increases. On the midpoint of Uttarayan (22nd March), the Sun again passes through the equator, making day and night equal, and this is the time of Mesha Sankranti, marking the beginning of the Indian New Year.
With this instrument, we can determine the Sun’s apparent longitude and declination. Using Palabha, the local latitude can be determined and directions can also be accurately known through this instrument. The Sun’s movement in Uttarayan and Dakshinayan is a result of Earth’s axial tilt.
