In Hindu astrology, the Navagraha (Sanskrit: नवग्रह, nine seizers or nine influencers) are major influencers on the living beings of mother Bhumi (Earth). They themselves are not causative elements but can be compared to traffic signs.
The Navagraha denote the nine celestial bodies – not the nine planets as it is frequently erroneously translated – which are central to astrological calculations (and beliefs). The Navagrahas are: the sun, the moon, mars, mercury, jupiter, venus, saturn, and the two shadow planets Rahu and Ketu.
Surya is the chief, the solar deity, one of the Adityas, son of Kasyapa and one of his wives – Aditi, Indra or Dyaus Pitar (depending on the version). He has hair and arms of gold. His chariot is pulled by seven horses, which represent the seven chakras. He presides as “Ravi” over “Ravi-var” or Sunday.
Surya is notably mentioned as the visible form of God that one can see every day. He is said to be of Sattva Guna and represents the Soul, the King, highly placed persons or fathers. According to Hindu mythology, among the more renowned progenies of Surya are Shani (Saturn), Yama (God of Death) and Karna (Mahabharatha). Invoking Gayatri Mantra or Aditya Hrudaya Mantra (Adityahridayam) are known to please the Sun God. The grain associated with the Sun is whole wheat and the number associated to the Surya is 1.
Chandra is a lunar deity. Chandra (moon) is also known as the Vedic Lunar deity Soma. He is described as young, beautiful, fair; two-armed and having in his hands a club and a lotus. He rides his chariot (the moon) across the sky every night, pulled by ten white horses or an antelope. He is connected with dew, and as such, is a god of fertility. He is also called Nishadipati (Nisha=night; Adipathi=Lord) and Kshuparaka (one who illuminates the night). As Soma, he presides over Somvar or Monday. He is of Sattva Guna and represents the Mind, the Queen or Mother.
Budha is the god of the planet Mercury and the son of Chandra (the moon) with Tara (Taraka). He is also the god of merchandise and protector of merchants. He is represented as being mild, eloquent and of greenish colour. He is represented holding a scimitar, a club and a shield, riding a winged lion in Ramghur temple. In other illustrations, he holds a sceptre and lotus and rides a carpet or an eagle or a chariot drawn by lions. He is of Rajas Guna and represents Communication. Budha presides over ‘Budh-var’ or Wednesday. In modern Tamil and Malayalam it is Budhan.
Brihaspati is the Guru of Devas, personification of piety and religion, the chief offerer of prayers and sacrifices. he is , represented as the Purohita of the gods with whom he intercedes for men. He is the Lord of planet Jupiter, and represents knowledge and teaching. According to Hindu scriptures, he is the guru of the Devas and the arch-nemesis of Shukracharya, the guru of the Danavas. He is also known as Guru, the god of wisdom and eloquence, to whom various works are ascribed, such as the “atheistic” Barhaspatya sutras.
He is of Sattva Guna, his Tattva or element is Akasha or ether, and his direction is north-east. He is described of yellow or golden colour and holding a stick, a lotus and his beads. He presides over ‘Guru-var’ or Brihaspativar -Thursday.
Shukra, Sanskrit for “clear, pure” or “brightness, clearness”, is the name of the son of Bhrigu and Ushana, and preceptor of the Daityas, and the guru of the Asuras, identified with the planet Venus (Shukracharya). He is of white complexion, middle-aged and of agreeable countenance. He is described variously mounted, on a camel or a horse or a crocodile. He holds a stick, beads and a lotus and sometimes a bow and arrow. The planetary period known as Shukra Dasha remains active in a person’s horoscope for 20 years. This dasha is believed to give more wealth, fortune and luxury to one’s living if a person has Shukra positioned well in his horoscope as well as Shukra being an important benefic planet in his/her horoscope. He presides over ‘Shukra-var’ or Friday. He is Rajas in nature and represents wealth, pleasure and reproduction.
Shani is embodied in the planet Saturn. The origin of word Shani (शनि) comes from the following: Shanaye Kramati Sa: (शनये क्रमति सः) i.e. the one who moves slowly. Saturn takes about 30 years to revolve around the Sun, thus it moves slowly compared to other planets, thus the Sanskrit name शनि. Shani is actually a demi-god and is a son of Surya (the Hindu Sun God) and surya’s wife Chhaya. It is said that when he opened his eyes as a baby for the very first time, the sun went into an eclipse, which clearly denotes the impact of Shani on astrological charts. He is depicted dark in colour, clothed in black; holding a sword, arrows and two daggers and variously mounted on a black crow or a raven. He is Tamas in nature and represents learning the hard way, Career and Longevity. His Tattva or element is air, and his direction is west. He presides over ‘Shani-var’ or Saturday.
Rahu is God of the Ascending / North lunar node. Rahu is the head of the demonic snake that swallows the sun or the moon causing eclipses, according to Hindu scriptures. During the Samudra manthan, the asura Rahu drank some of the divine nectar. But before the nectar could pass his throat, Mohini (the female avatar of Vishnu) cut off his head. The head, however, remained immortal and is called Rahu, while the rest of the body became Ketu. It is believed that this immortal head occasionally swallows the sun or the moon, causing eclipses. Then, the sun or moon passes through the opening at the neck, ending the eclipse. He is depicted as a dragon with no body, riding a chariot drawn by eight black horses. He is a Tamas Asura who does his best to plunge any area of one’s life he controls into chaos. The rahu kala is considered inauspicious.
Ketu is the Lord of Descending/South lunar node. Ketu is generally referred to as a “shadow” planet. He is considered as Tail of the Demon Snake. It is believed to have a tremendous impact on human lives and also the whole creation. In some special circumstances it helps someone achieve the zenith of fame. He is Tamas in nature and represents supernatural influences.
Astronomically, Ketu and Rahu denote the points of intersection of the paths of the Sun and the Moon as they move on the celestial sphere. Therefore, Rahu and Ketu are respectively called the north and the south lunar nodes. The fact that eclipses occur when the Sun and the Moon are at one of these points, gives rise to the story of the swallowing of the Sun and the Moon.
Source: https://en.wikipedia .org/wiki/Navagraha