Aditya means “whose mother is ADITI,” the Vedic goddess. The father of the Adityas is usually said to be the RISHI Kashyapa, a famous Vedic rishi. The Adityas are sometimes referred to as seven, sometimes eight, and sometimes 12 in number. The Vedic list is seven or eight. The list of seven includes VARUNA, MITRA, ARYAMAN, BHAGA, DAK-SHA, ANSHA, and SURYA or SAVITRI. The list of eight sometimes includes Martanda, who is said to have been excluded by his mother.
When 12 Adityas are listed, in later times, they represent the 12 months of the year; they are Dhatri, MITRA, ARYAMAN, RUDRA, SURYA, Bhaga, VIVASVAT, PUSHAN, SAVITRI, TVASHTRI, and VISHNU. In some lists AGNI, the god of fire, or even INDRA, the king of the gods, is referred to as an “Aditya.”
Further reading: Joel P. Brerton, The Rg Vedic Adityas (New Haven, Conn.: American Oriental Society, 1981); Pravesh Saxena, Aditya from Rgveda to the Upanisads (Delhi: Parimal, 1992); W. J. Wilkins, Hindu Mythology, Vedic and Puranic (Calcutta: Rupa, 1973).
Encyclopedia of Hinduism. A. Jones and James D. Ryan. 2007.