The nakshatra is the layer of Jyotish with no real Western equivalent: a second zodiac, finer than the signs, laid over the same circle and read mainly through the Moon.
A nakshatra is one of 27 lunar mansions dividing the sidereal zodiac into equal arcs of 13 degrees 20 minutes. The Moon crosses roughly one per day, completing the set in a sidereal month of about 27.3 days. Each nakshatra carries a planetary lord, a presiding deity, a symbol, and a temperament, and each is quartered into 4 padas of 3 degrees 20 minutes. The nakshatra holding the Moon at birth, the janma nakshatra, sets both the starting lord and the starting balance of the Vimshottari dasha sequence, which is why Jyotish treats it as the single most load-bearing point in the chart. Astrolium reports the nakshatra and pada of every planet in its Jyotish chart, not only the Moon.
How the 27 divisions work
The sidereal circle of 360 degrees divided by 27 gives 13 degrees 20 minutes per nakshatra, which is the arc the Moon covers in roughly a day. That is the origin of the scheme: the mansions track where the Moon stays each night, and the names are old, appearing in the Vedic corpus well before the 12-sign zodiac was absorbed into Indian practice from Hellenistic sources.
A 28th mansion, Abhijit, survives in some lineages as a short interval carved out of the end of Uttara Ashadha and the start of Shravana. Most modern Jyotish, and every calculation in Astrolium, works with the even 27.
Each nakshatra splits into 4 padas of 3 degrees 20 minutes. The pada is not decorative: the 108 padas across the circle map one to one onto the signs of the D9 Navamsa, so the pada a planet occupies determines its Navamsa placement. Knowing the pada means knowing something about the planet's condition in the varga chart before you cast it.
The lords and the dasha link
Nine lords run through the 27 mansions in a fixed order, three times around: Ketu, Venus, Sun, Moon, Mars, Rahu, Jupiter, Saturn, Mercury. Ashwini, Magha and Mula belong to Ketu; Bharani, Purva Phalguni and Purva Ashadha to Venus; and so on.
That ordering is the hinge between the chart and its timeline. Whichever nakshatra holds the Moon at birth, its lord runs the first mahadasha, and the fraction of the mansion the Moon has already crossed tells you how much of that period has elapsed before the first breath. A Moon three quarters of the way through Rohini opens life with a quarter of a Moon mahadasha, roughly 2.5 years of a 10-year period. The mechanics are set out in the Vimshottari dasha entry.
This is also why birth time matters so much in Jyotish. The Moon moves about 13 degrees a day, so it crosses a nakshatra boundary roughly once every 24 hours, and a chart recorded to the nearest hour can sit on the wrong side of one.
Reading a nakshatra
Beyond the lord, each mansion carries attributes that practitioners use directly: a deity, a symbol, a gana classification (deva, manushya or rakshasa), a yoni animal, and a gender and quality assignment. Krittika is ruled by the Sun with Agni as deity and a blade as symbol, and planets there tend to read as cutting and purifying. Rohini, ruled by Venus with a cart as symbol, reads as fertile and acquisitive. Ardra, ruled by Rahu with a teardrop, reads as storm and dissolution.
These attributes do real work in matching and in electional practice. Gana and yoni are two of the eight kutas scored in kundli matching, and the Moon's daily nakshatra is one of the five limbs of the panchang.
In Astrolium
The Jyotish workspace gives nakshatras their own analysis tab and reports the mansion and pada for every graha, with the mansion's ruler named, rather than restricting the layer to the Moon. Because Graha Drishti and the divisional charts are computed from the same request, you can follow a planet from its nakshatra pada into its D9 position in the Compare view.
The free Vedic birth chart calculator returns the nakshatra, its lord and the pada for each planet along with the running dasha, without an account. For the wider framework, including why the sidereal circle sits about 24 degrees away from the tropical one, read the Vedic astrology guide and the ayanamsa entry.