he Indian Astrology [Jyotish],
which predates almost all written text except for the Vedas, is actually a part and parcel of Vedas called the Vedang, or a limb of Vedas. The Vedas are the religious scriptures of the great seers and sages of India.
As per Jyotish, the sixth Vedang, the Celestial Sky is divided into parts for easier computation of characteristics.

The easier references are the 12 Zodiac Signs to which most of us are familiar, but there is a more precise division and they are referred to as Nakshatras.
The Nakshatras are one of the oldest references we have to astrology from the Rig Veda. The Nakshatras are like the zodiacal signs but more specific. Their meanings are derived from the constellations, fixed stars and the mythology behind these portions in the sky. The lore associated to Nakshatras are rich in meaning and have ruling deities that reveal the stories or myths that bring to life the essence referred to in our own lives.
The sky as we know it can be referred to as a 360 degree orb, which is divided into 27 almost equal parts [although for ease of computation we consider them equal] of 13 degree 20 minutes each.
The Nakshatras are divisions of 13 degrees 20 minutes starting from zero Aries and ending at 30 degrees of Pisces, 13.20 divided into the 12 signs is 27. The nakshatras are referred to as the lunar mansions because the Moon moves approximately 13.20 per day, therefore resides in one nakshatra per day. The personal planet in which the nakshatra resides will reveal deep information about the individual in relation to the meanings of the houses (area of life), and what houses the planet rules.
Nakshatras are epitome of characterization of a personality and are the best tool to compute compatibility between two individuals, especially for the purpose of marriage. Though the so called learned people now dismiss it as an obsolete art, but I have witnessed hundreds of cases where a marriage which is decided out of love between two individuals faces more rough patches than that settled after due deliberation of Nakshatra Compatibility. As it’s a holistic approach to the life of an individual.
For example, the planet that rules the 7th house (indicating a person’s spouse), will reveal detailed information about the spouse by the description of that nakshatra. If Aries is the sign of the 7th house, then Mars, the ruler of Aries (the nakshatra where Mars resides) will describe the spouse. If Mars is in the nakshatra Magha, the spouse would have all the kingly qualities of Magha.
Each Nakshatra has its particular power or Shakti. These are also the powers of the Devatas or the Demi God or the ruling Deity of the Nakshatras. These Powers influence the Characteristics of an individual throughout his life, be it healing, worship, marriage or death.
These teachings are derived from an ancient Vedic text called Taittiriya Brahmana I.5.1 and from the commentary of Bhattabhaskara Mishra.