This Fakirs Worshipping "The Sun" vintage post card is not in my own collection. One person from United Kingdom giving me permission for using his Indian vintage post cards images in my Heritage of India blog. Sir thank you very much for your encouragement.
In India it is a common practice of Worshipping the Sun. Hindu priests and brahmins worshipping the Sun in the form of Gayatri Maa and performing Sandhyavandanam. Hindu Fakirs performing Soorya Aaradhana by Chanting Mantras. In India different sects of people worshipping the Sun in different ways and forms and each of these methods are their own and unique. But worshipping the Sun is an age old practice in India since ancient times.
Performing Sandhyavandana and Gayatri Mantra reciting is another form of Worshipping "The Sun". Most Indian people consider by performing Sandhyavandana in 3 periods of Sandhya (Prataha, Madhyahna and Sayam Sandhya periods) then it goes to Sun (Sooryadeva).
For more information about Sandhyavandanam, Gayatri Mantra reciting and Sun worshipping please visit my Gayatri Mantra blog http://gayatri-mantra-meditation.blogspot.in/ which i created especially for Gayatri Mantra.