Nakshatra is a term that is used to denote the lunar mansion in Hindu astrology. According to Indian or Hindu astrology the zodiac is divided into 360 degrees. There are 27 Nakshatras or constellations in it and each constellation is of 13 degrees and 20 minutes. Each nakshatra has a unique name associated to it and these names are related to the most prominent asterisms in their respective sectors. Initially the zodiac was divided into 12 rashis for the sake of convenience but later the ancient seers further divided them into 27 nakshatras or constellations for the call of precession. Today these constellations are one of the most important components of Astrology.
The name of the 27 nakshatras are as follows:-
This list was first found in the Vedanga Jyotisha which is a text that is dated to the final centuries of BCE. It predates the influence of Hellenistic astronomy of vedic tradition.
In vedic astrology each constellation is identified with a star. For the process of convenience the sky which is of 360 degree is divided into 27 subdivisions, each sub-division is of 13.20 degrees. Each of these nakshatras is then further divided into four padas or quarters, each quarter of 3 degrees and 20 minutes. The first Rashi, which is Mesha has 30 degrees and contains the entire 4 padas of the 1st start constellation Ashwini, the entire 4 padas of the second star constellation which is Bharani and the first pada of the third star constellation Krittika. In this way each rashi consists of 9 padas.
There is another way of dividing the nakshatras which is as follows - they are divided under three heads of Deva (divine), Nara (human) and Rakshasa (demonic). They are also divided in terms of gender and varna (caste) and these nakshatras are also ascribed with qualities such as colour, presiding deity, merits and ruler ship of body parts, planets etc. The starting point for the nakshatras is the point on the ecliptic directly opposite to the star Spica called Chitra in Sanskrit.
According to the classical Hindu mythology like Mahabharata and Harivamsa the creation of the nakshatras is attributed to Daksha. In these mythologies, these nakshatras are personified as daughters of the deity and as mythological wives of Chandra who is the moon god, or alternatively the daughters of Kashyapa who is the brother of Daksha. Each of these Nakshatras is ruled by a lord which is one of the nine grahas or planets. They are in the following sequence - Ketu (South Lunar Node), Shukra (Venus), Ravi or Surya (Sun), Chandra (Moon), Mangala (Mars), Rahu (North Lunar Node), Guru or Brihaspati (Jupiter), Shani (Saturn) and Budha (Mercury). To cover all the 27 nakshatras, this cycle repeats itself three times. These lords assigned to each nakshatras determines the planetary period known as the dasha which is very important in forecasting the future of any individual according to Hindu astrology.
In Hindu astrology, Nakshatras play a very important role. Once a child is born, they should be given an auspicious first name corresponding to the Nakshatra of the child. To derive the name one should first check and see to which nakshatra the moon is in at the moment of birth. This will give you four different sounds and you should be able to pick one sound out of that four that relates to the pada or division of the Nakshatra. Each Nakshatra has four padas and four sounds and each pada is equal width. In each nakshatra the moon will remain for approximately one day.