What is Surya Tilak? The system, why it is done. Understand the science behind the ceremony

On Ram Navami, the Sun's rays will fall on the forehead of Ram Lalla in Ayodhya, a 'Surya tilak' made possible by an elaborate mechanism involving mirrors and lenses. This is the first Ram Navami since the consecration of the Ram idol at the new temple on January 22. The system was tested by the scientists on Tuesday. 

The science behind the Surya Tilak

"The basic objective of the Surya Tilak project is to focus a 'tilak' on the forehead of Shri Ram idol on every Shri Ram Navami day. Under the project, sunlight will be brought on the forehead of Lord Ram at noon on Shri Ram Navami in the Chaitra month every year," Dr S K Panigrahi, scientist at CSIR-CBRI Roorkee, who was associated with the project said. Elaborating further, Panigrahi said, "The position of the Sun changes every year on the day of Shri Ram Navami. Detailed calculations show that the date of Shri Ram Navami repeats every 19 years." 

58 cm tilak, lasting a little over 3 minutes
The planned tilak size is 58 mm. The exact period of tilak on the forehead centre is about three to three-and-a-half minutes, with two minutes of full illumination. During the Surya tilak, devotees will be allowed inside the Ram temple. Around 100 LEDs are being put up by the temple trust, and 50 by the government, which will show the Ram Navami celebrations. People will be able to see the celebrations from where they are present. 

Done with utmost accuracy

Dr D P Kanungo, chief scientist at CSIR-CBRI, Roorkee said, "Actually this is meticulously planned, designed and implemented to achieve utmost accuracy." This will be a testament to our scientific acumen and indigenous technological development to showcase before our countrymen who have all the faith in and support to our scientific community, he said. 

What if it is a cloudy day
Kanungo said, "That's the limitation. We don't wish to do with artificial light because of the faith and belief of our people." In consultation with the Indian Institute of Astrophysics (IIA), Bangalore, the CSIR-CBRI, Roorkee team has developed a mechanism for a 19-year period to steer the sunlight from the third floor of the temple to the 'garbha griha'. 

Developed by CBRI

The detailed complete design to bring the sunlight to the garbha griha is developed by CBRI, with the IIA providing consultancy for the optical design. The fabrication of optical elements, pipes, tilt mechanism and other related components are carried out by Optics and Allied Engg Pvt Ltd (Optica), a Bangalore-based company. 

Pilot done
Before implementing the opto-mechanical system in the Ram temple for Surya tilak, a scaled down model suitable for the Roorkee locality has been successfully validated. A full scale model has been successfully validated at Optica site at Bangalore in March 2024. The CSIR-CBRI, Roorkee team along with IIA Bangalore and Optica Bangalore completed the installation in the first week of April, and repeated trials have been done.

Four mirrors and four lenses
The opto-mechanical system consists of four mirrors and four lenses fitted inside the tilt mechanism and piping systems. The complete cover with aperture for the tilt mechanism is placed at the top floor to divert the Sun rays through mirrors and lenses to the garbha girha. The final lens and mirror focus the Sun rays to the forehead of Shri Ram facing towards the east. The tilt mechanism is used to adjust the first mirror tilting for sending the Sun rays towards the north direction to the second mirror for making the Surya tilak every year on Shri Ram Navami day.

All the piping and other parts are manufactured using the brass material. The mirrors and lenses which are used are of very high quality and durable to sustain for a long period. The inner surface of pipes, elbows and enclosures are black powder coated to avoid scattering of sunlight. Also at the top aperture, IR (infra red) filter glass is used to restrict the Sun heat wave to fall on the forehead of the idol.