Here is your short paragraph on Ratha Saptami:
This is a Pan-Indian festival that falls in the month of Margsheesh (November- December). It is an auspicious day when devotees belonging to all castes perform sun worship and visit holy places and temples.
In Tamil Nadu, this falls on the 7th day of the bright fortnight in Tai (January-February). At Suriyanar Koil near Kumbakonam, the devotees worship the Sun and other planets.
While having a sacred bath, people place a layer of the leaves of erukku on the head. It is believed that it is beneficial to do so because the leave of erukku stated to possess miraculous properties on the occasion.
If the festival occur on Sunday or the day with the star Rohini, it is considered highly auspicious.