What a nakṣatra is

Twenty-seven, because of the Moon

The Moon returns to the same star in about 27.3 days. Dividing its path into twenty-seven parts therefore gives segments the Moon crosses in roughly one day each — which is exactly what makes them useful for a daily almanac.

Each segment is 13°20′ wide and is named for a marker: Aśvinī, Bharaṇī, Kṛttikā, Rohiṇī, and so on to Revatī. Some names point at a single bright star, some at a small group.

Each is further divided into four pādas, quarters of 3°20′, which is the level of detail used when a name syllable is chosen for a newborn.

Measured against the stars, not the seasons

Nakṣatra boundaries are sidereal: they are fixed to the stars. The Western zodiac in common use is tropical: it is fixed to the equinox, which slides backwards against the stars by about fifty seconds of arc a year.

Over two thousand years that drift has grown to more than twenty-three degrees. The correction is the ayanāṃśa, and its value is a choice an almanac has to declare. Different declared values move every nakṣatra boundary by minutes to hours — which is a common reason two almanacs disagree.

Natures, and what they are used for

Traditional practice groups the nakṣatras by nature — among them the gentle, the fixed, the swift, the fierce and the sharp — and treats some as better suited to particular kinds of undertaking than others. This site’s daily reference uses those groupings, and names which one applies rather than reducing the day to a score.

This is where a Panchāṅgam stops being astronomy and becomes tradition, and traditions differ. The groupings this site uses are stated on the methodology page; whether a particular ceremony in your family follows them is a question for Gurukkal.

What a family may do

• If you know your janma nakṣatra, keep a note of it — it is asked for at naming ceremonies, at marriage matching, and for the annual observance some families keep on that day.
• If you do not know it, it can be worked out from a birth date, time and place. Gurukkal can do this; a calendar cannot, because it needs the birth time.

Often misunderstood

• That a nakṣatra is a Western star sign. They are different divisions of a different circle, measured in a different frame.
• That a “fierce” nakṣatra is a bad day. The traditional reading is that it is better suited to decisive acts than to gentle beginnings — a matter of fit, not of misfortune.

Where traditions differ

• Some traditions count twenty-eight nakṣatras, inserting Abhijit between Uttarāṣāḍhā and Śravaṇa. The twenty-seven-fold division is the one used for the daily almanac here.

Explaining it to a child

The Moon takes about a month to go all the way round the sky. On the way it passes twenty-seven groups of stars, like twenty-seven houses along a road. Your birth star is the house the Moon was in on the day you were born.