Using the 1792 illustrations from the site three scientists recognized newer additions to the temple structure that in some ways hides the intent of the original builders. Devotees throng to the temple on Makar Sankranti day (Jan 14) every year when the rays of the Sun fall on the Shiva lingam. But sun’s rays could during earlier centuries enter the sanctum on winter solstice day. The temple was deliberately offset from the customary cardinal E-W direction common to temple architectures. Without the newly added temple boundary walls the shadow cast by one disc onto the other could be used to calibrate the movement of Sun and the Moon around solstice days. Over time, local residents only remembered the names of the two disc structure and not their true purpose.
Eighteen centuries ago winter solstice coincided with Makar Sankaranti. Winter solstice was one of the most significant day of the year during Vedic times when annual fire rituals were timed to start on that day. Makar Sankranti celebrations of today is distinct from it and yet many confuse Makar Sankranti to be the start of Uttarayana. Ancient calendar makers and astronomers appear to have designed the temple complex and actively used it. The idol of Agni in this temple has a form that is distinctly Vedic. Vedic mantras invite Agni in this this form to Yagna rituals.
The initial design of the site must date back to the time when Vedic rituals were wide spread even though the temple is stylistically attributed to the seventh century. It has been a tradition for prominent kings during historic times to contribute major architectural embellishments to ancient worship sites. Archeological dating methods have progressed considerably in dating ancient brick structures. Perhaps some new technique will soon date cave structures more accurately.