Swetharanyeswarar Temple at Thiruvenkadu, the fourth Navagraha sthalam of the 9 Navagraha Temples in Tamil Nadu, is the abode of Bhudhan or Bhudha (planet Mercury). Thiruvenkadu Bhudha Sthalam is located near Poompuhar, around 10 km from Sirkazhi.
The presiding deity is Lord Shiva as Swetharanyeswarar and Goddess Parvati as Brahma Vidya Nayaki Ambal (Brahmavidyanayaki). Swetharanyeswarar Temple enshrines a separate sanctum sanctorum for Bhudhan or Bhudhan, one the nine Navagrahas and the bestower of wisdom and wealth.
The name Thiruvenkadu means 'sacred white forest' ('Ven' means white and 'Kadu' means forest). It is said that this place was surrounded by thick forests on all sides and when seen from a distance, it looked white, and hence the name. In Sanskrit it is known as Swetaranyam ('Swetam' means white and 'Aranyam' means forest). The place also bears various names such as Jnana-aranya, (forest of wisdom), Patala Kailas and Aadi Chidambaram.
Thiruvenkadu temple is surrounded by five prakarams known as pancha prakarams. Here the Lord is consecrated in His forms as Aghoramurthi (manifestation of His wild and angry form) and Nataraja (a manifestation of Shiva, assumed as the Lord of Dance).
Agora Murthi is the main God in this temple. It is said that Agora Murthi was one of the furious incarnations of Lord Shiva. There was an Evil named "Padmasuran" in Thiruvenkadu. He had a deep meditation on Lord Brahma for power. Being satisfied on his meditation, Lord Brahma offered him many powers. But he used those powers in a wrong ways. He started to torture the saints and innocent peoples. All the saints and peoples requested Lord Shiva to put an end to his evil. Lord Shiva took incarnated as 'Agora Murthi' and killed Padmasuran under a tree (now located in Thiruvenkadu temple, back to the entrance of Agora Murthi).
The Nataraja image holds seven instruments and weapons, namely, Vetalam, Khadgam, Udukku, Mani, Kedayam, Kapalam and Trisulam.
Lord Shiva performs seven forms of dance or Tandavas, viz Ananda tandavam, Sandhya tandavam, Samhara tandavam, Tripuranta tandavam, Urdhva tandavam, Bhujanga tandavam and Lalita tandavam here.
Lord Shiva is present here with five faces viz Easanam, Tatpurusham, Aghoram, Vamadevam and Sadyojatam, representing five directions and aspects of Lord Shiva. Easanam is facing the sky and represents purity, Vamdevam faces north and represents sustenance, Tatpurisha faces east and represents spirituality that has destroyed the ego, Aghoram faces south and represents the destructive and regenerative aspect of Shiva, Sadyojatam faces west and represents creation.
Devi in Her divine form of Bhadrakali has a separate shrine. Besides, there are separate shrines for Ashta Lakhsmis and the Navagrahas.
Swetharanyeswarar temple has three theerthams (holy tanks) called as Agni Theertham, Surya Theertham and Chandra Theertham which are said to have been created out of the three drops which fell from Lord Shiva's eyes when he was dancing.
The sthala vrikshams are also three in number - Vilvam, Vadaval and Konrai.
The stone inscriptions on the walls of the temples depict important historical information on the Chola Dynasty and about several kings of Vijayanagar.
The posture of Nandi at the entrance is another unique feature here. It bears nine scars on its body and is seated at the entrance of Devi's shrine. Marutwasura, an asura, was troubling the Rishis and the people of Thiruvenkadu. The people prayed to Lord Shiva. Lord Shiva sent Nandi to fight the demon. Marutwasura was defeated by Nandi and thrown into the sea. Marutwasura through his penance obtained sula from Lord Shiva. The demon then returned with greater intensity to attack the innocent people. Once again, at the request of the devotees, Shiva sent Nandi. However, on this occasion, Nandi could not fight the demon as the demon had the Sula of Shiva. The demon caused wounds on Nandi's back with the Sula.