In Hinduism, Âdityas (Sanskrit: आदित्य Ādityá, pronounced [aːditjə]), meaning "of Aditi", refers to the offspring of the goddess Aditi and her husband the sage Kashyapa. The name, Aditya, in the singular, is taken to refer to the Sun God, Surya.
The Bhagavata Purana lists a total of twelve Adityas as Sun-gods. In each month of the year a different Aditya is said to shine. According to the Vaishnava tradition of Hinduism, each of these Adityas is a different expression of the Supreme God Vishnu in the form of the Sun-God.
|Mantra||Aum Adityebhyah Namah|
|Mount||Horses and many others|
In the Rigveda, the Âdityas are the seven celestial deities, sons of Âditi,
The eighth Âditya (Mārtanda) was rejected by Aditi, thus leaving only seven sons. In the Yajurveda (Taittirīya Samhita), their number is given as eight, and the last one is believed to be Vivasvān. Hymn LXXII of the Rig Veda, Book 10, also confirms that there are nine Adityas, the eighth one being Mārtanda, who is later revived as Vivasvān. 
"So with her 'seven sons', Aditi went forth to meet the earlier age. She brought Mārtanda thitherward away to spring to life and die again"
The Âdityas of the Rig Veda are "devas", a distinct class of gods and are different from other groups such as the Maruts, the Rbhus or the Viśve-devāḥ (although Mitra and Varuna are also associated with the latter). 
In the Bhagavata Purana, the names of 12 Adityas are given as:
In each month of the year, it is a different Aditya who shines as the Sun-God. As Indra, Surya destroys the enemies of the gods. As Dhata, he creates living beings. As Parjanya, he showers down rain. As Tvashta, he lives in the trees and herbs. As Pusha, he makes foodgrains grow. As Aryama, he is in the wind. As Bhaga, he is in the body of all living beings. As Vivasvana, he is in fire and helps to cook food. As Vishnu, he destroys the enemies of the gods. As Amshumana, he is again in the wind. As Varuna, he is in the waters and As Mitra, he is in the moon and in the oceans.
The Aditya have been described in the Rig Veda as bright and pure as streams of water, free from all guile and falsehood, blameless, perfect.
This class of deities has been seen as upholding the movables and immovable Dharma. Adityas are beneficent gods who act as protectors of all beings, who are provident and guard the world of spirits and protect the world.In the form of Mitra-Varuna, the Adityas are true to the eternal Law and act as the exactors of debt.
In present-day usage in Sanskrit, the term Aditya has been made singular in contrast to Vedic Adityas, and are being used synonymously with Surya, the Sun. The twelve Adityas are believed to represent the twelve months in the calendar and the twelve aspects of Sun. Since they are twelve in number, they are referred as Dvadashadityas.
The 12 Adityas are basically the monthly suns which is the ancient word for the earth moon barycenter for lunar month. These are also called as the 12 purushas pertaining to the 12 lunar months of the year. Here the months refer to the lunar months. In astronomy the lunar months with a solar sankranti is said to have an Aditya or purusha. The month without a sankranti is said to be neutar and is said to be extra month or the intercalary lunar month.
According to the Linga Purana, the Adityas are:
The Vedas do not identify the Âdityas and there is no classification of the thirty-three gods, except for in the Yajurveda (7.19), which says there are eleven gods in heaven (light space), eleven gods in atmosphere (intermediate space), and eleven gods in earth (observer space). In the Satapatha Brahmana, the number of Ādityas is eight in some passages, and in other texts of the same Brahmana, twelve Adityas are mentioned.  The list of 12 Adityas is as follows:
Adityas are responsible for proper functioning of the universe and in Hindu cosmology they are given lordship over celestial constellations, called Nakshtras in Jyotish. Nakshatras are forces of universal intelligence which are intertwined with the birth-death cycle of life, identity of all created beings, events and day to day consciousness in our lives. Adityas manage the Shakti of the nakshatras. Here are few examples.
This makes Vedic Adityas not some conceptual, abstract, or mythological characters in a story book, but part of the visible cosmology and the everyday realities of our daily lives. We manifest their qualities in our lives and as such are part of the divine ourselves.
Avestan Ahura derives from Indo-Iranian Asura, also attested in an Indian context as RigVedic Asura. Avestan Daivas are considered synonymous to Vedic Devtas, or Adityas.
Vedas and Zoroastrian Avesta have a common name Ahura-Mazda, which may refer to some Vedic God (sometimes in Rigveda some demigods or devatas are worshipped as "asura", which in Zoroastrianism is Ahura-Mazda. See also: Vishnu sahasranama (Aditya: 39 aadityah, 563 aadityah - Son of Aditi). Ahura-Mazda is commonly considered a link between Avestan Zoroastrianism and Asuras of Vedic literature, however there is no one specifically called Ahura Mazda in the Vedas.
For evolutionary reasons Asuras and Devtas fought great battles. Adityas, sons of Rishi Kashyap and Aditi always followed the guidance of Trimurti, or the Trinity of Brahma, Vishnu and Shiva and are responsible for proper functioning of the universe, Asuras challenged their authority at various occasions. Most significantly there are constant battles for the Elixir of Immortality, called Amrit, between the two. This could explain why Avestan Asura-Mazda advised his followers to stay away from Daivas or Vedic Devtas, calling them untrustworthy and unscrupulous shining beings to be avoided at all cost.
Historically there was little difference between Asuras and Devtas during the times of Veda. Many of them were highly regarded, and comparable to necessary forces of nature. In post Vedic era especially in the narratives of Puranas many Asuras became synonymous with trouble makers, who come into conflict with Mahadev Shiva, Vishnu, Brahma and Indra wreaking havoc on civilizations. There are some famous Asuras-Devtas conflicts including Samudra Manthan regarding churning of the Ocean. There are some famous Asuras such as Vritra-Asur, Bana-Asur,and Bhasma-Asura who challenge Adityas and specifically Indra, the king of Devtas.
Going by Sanskrit definitions Asura is opposite of Sura. Sura is anything that is in harmony, in tune with laws of nature, called eternal truth or Sanatan Dharam. A-Sura is a being or force of nature which is chaotic, disorderly, and out of tune.
12 (twelve) is the natural number following 11 and preceding 13. The product of the first three factorials, twelve is a superior highly composite number, divisible by 2, 3, 4, and 6. It is central to many systems of counting, including the Western calendar and units of time, and frequently appears in the Abrahamic religions.Konark Sun Temple
Konark Sun Temple is a 13th-century CE sun temple at Konark about 35 kilometres (22 mi) northeast from Puri on the coastline of Odisha, India. The temple is attributed to king Narasingha deva I of the Eastern Ganga Dynasty about 1250 CE.Dedicated to the Hindu 'god Surya, what remains of the temple complex has the appearance of a 100-foot (30 m) high chariot with immense wheels and horses, all carved from stone. Once over 200 feet (61 m) high, much of the temple is now in ruins, in particular the large shikara tower over the sanctuary; at one time this rose much higher than the mandapa that remains. The structures and elements that have survived are famed for their intricate artwork, iconography, and themes, including erotic kama and mithuna scenes. Also called the Surya Devalaya, it is a classic illustration of the Odisha style of Architecture or Kalinga Architecture .The cause of the destruction of the Konark temple is unclear and remains a source of controversy. Theories range from natural damage to deliberate destruction of the temple in the course of being sacked several times by Muslim armies between the 15th and 17th centuries. This temple was called the "Black Pagoda" in European sailor accounts as early as 1676 because its great tower appeared black. Similarly, the Jagannath Temple in Puri was called the "White Pagoda". Both temples served as important landmarks for sailors in the Bay of Bengal.
The temple that exists today was partially restored by the conservation efforts of British India-era archaeological teams. Declared a UNESCO world heritage site in 1984, it remains a major pilgrimage site for Hindus, who gather here every year for the Chandrabhaga Mela around the month of February.Thirty-three gods
The Thirty-three deities (Sanskrit: trayastriṃśat) is a pantheon of Vedic deities, some of Vedic origin and some developed later. All the Vedic deities are called tri-piṣṭapa, and there are three kinds of them — the Ādityas, the Vasus and the Rudras — beneath whom are the other demigods, like the Maruts and Sādhyas. Tridasha generally includes a set of 31 deities consisting of 12 Ādityas, 11 Rudras, and 8 Vasus with the identity of the other two deities that fill out the 33 varies.
The 33 are:
Eight Vasus (deities of material elements) – Dyauṣ "Sky", Pṛthivī "Earth", Vāyu "Wind", Agni "Fire", Nakṣatra "Stars", Antarikṣa "Atmosphere" or "Space", Sūrya "Sun", Chandra "Moon"
Twelve Ādityas (personified deities) – Vishnu, Aryaman, Indra (Śakra), Tvāṣṭṛ, Varuṇa, Bhaga, Savitṛ, Vivasvat, Aṃśa, Mitra, Pūṣan, Dakṣa. This list sometimes varies in particulars.
Eleven Rudras, consisting of:
Five abstractions – Ānanda "bliss", Vijñāna "knowledge", Manas "thought", Prāṇa "breath" or "life", Vāc "speech",
Five names of Śiva – Īśāna "revealing grace", Tatpuruṣa "concealing grace", Aghora "dissolution/rejuvenation", Vāmadeva "preserving aspect", Sadyojāta "born at once"
Ātmā "self"Other sources include the two Aśvins (or Nāsatyas), twin solar deities.