'Surya tilak' to grace idol every Ram Navami despite changes in Sun's position

The ‘surya tilak’ that illuminated Ram Lalla idol’s forehead in Ayodhya on Wednesday will be an annual affair on Ram Navami.

However, since the temple is yet to be fully constructed, the final design of the optical mechanism that made the ‘surya tilak’ possible needs to be tweaked as the position of the Sun changes every year on Ram Navami, said Abhay Karandikar, secretary of the Department of Science and Technology.

There is no way for direct sunlight to enter the temple’s sanctum sanctorum. Thus, an elaborate mechanism involving mirrors and lenses (called opto-mechanical system) was used through which sun rays were directed at the forehead of the Ram idol.

The mechanism was devised by scientists at the Indian Institute of Astrophysics (IIA), an autonomous body under the Department of Science and Technology, in collaboration with Roorkee’s Central Building Research Institute.

The mechanism used for the ‘Surya Tilak’. (Source: X/@karandi65)

In a thread on X, Karandikar said the IIA team calculated the Sun’s position, designed and optimised the optical system, and performed the integration and alignment at the site.

The government official said the IIA team modified the optomechanical system to suit the present structure as the temple was not fully complete. It will take another two years for the construction of the Ram Mandir complex to be completed.Â

“The team performed image optimisation. This design, with four mirrors and two lenses, was executed for the Surya Tilak,” he said.

The final design that will be used to deflect the sun’s rays towards the idol’s forehead will have four mirrors and four lenses. “It will be implemented once the full temple is constructed by placing the mirrors and lenses in their permanent fixtures,” Karandikar said.

However, he pointed out that the Ram Navami date changes every year as it follows the Lunar Calendar. Due to this, the position of the sun in the sky will also change every year on Ram Navami.

“Detailed calculations show that the English calendar date of Ram Navami repeats every 19 years. Calculating the position of the Sun in the sky on these days requires expertise in astronomy,” he said.

He further said the final design of the system will allow sufficient light to fall on the idol for about six minutes.

“Opto-mechanical design of the lens and mirror holder assembly, and manual mechanism were carried out to shift the position of the first mirror according to the position of the Sun in the sky. This helped the entire system to work flawlessly for the Surya Tilak to be carried out successfully,” Karandikar said.