What is a Nakshatra?
The Tamil (and broader Indian) astronomical tradition divides the sky into 27 Nakshatras — lunar mansions or star-houses that the Moon passes through during its 27.3-day orbit around Earth. Each Nakshatra spans approximately 13° 20′ of the zodiac. The Moon spends roughly one day in each mansion, making Nakshatras a natural lunar calendar — far older than the zodiac signs we commonly use today.
Every Nakshatra has a ruling planet, a presiding deity, a symbol, a set of qualities, and a role in timing festivals, rituals, and auspicious moments. They are the backbone of the Tamil Panchangam.
Karthigai — The Star Cluster
Karthigai corresponds to the Western constellation cluster known as the Pleiades, located in the constellation Taurus. In Tamil, the cluster is called கார்த்திகை (Karthigai) or அறுமீன் (Arumeen — "the six stars," referring to the six most distinctly visible). In Sanskrit it is known as Krittika.
The Pleiades cluster contains over 1,000 stars, of which seven are visible to the naked eye under dark skies — the legendary "Seven Sisters" of Greek mythology, and the six-star motif in Tamil tradition. The cluster lies approximately 444 light-years from Earth and is relatively young in stellar terms — about 100 million years old.
How to Find Karthigai in the Night Sky
- Look for the constellation Taurus (the Bull).
- The Pleiades appears as a tight, fuzzy cluster of stars in the "shoulder" region of Taurus.
- Best visible from November to April in the Tamil Nadu night sky — precisely the season of the Karthigai month.
- In November–December (Tamil month of Karthigai), the cluster rises high overhead at midnight and is unmistakable.
- It appears as a small "smudge" to the naked eye but resolves into many individual stars through binoculars.
Karthigai and Lord Murugan
In Tamil tradition, Karthigai Nakshatra is closely associated with Lord Murugan (முருகன்) — the Tamil god of war, youth, beauty, and wisdom, known also as Kartikeya or Skanda in Sanskrit. According to Puranic tradition, Murugan was raised by the six Krittika star-maidens — one star-mother for each of his six faces (Shanmukha — "the six-faced one").
This cosmic origin story explains why Murugan is Tamil Nadu's most beloved deity, why his temples are always on hilltops (close to the sky), and why the Karthigai month is considered his sacred month.
Karthigai Deepam — The Festival of Lights
Karthigai Deepam (கார்த்திகை தீபம்) is one of the oldest Tamil festivals, celebrated on the full moon day of the Tamil month of Karthigai (November–December) when the Moon is in the Karthigai Nakshatra. On this night, every Tamil household lights lamps — row upon row of oil wicks — transforming streets into rivers of fire.
The most spectacular celebration is at Thiruvannamalai, where a massive beacon fire is lit on the peak of the sacred hill Arunachala. The flame is visible for miles and symbolises the cosmic pillar of light — the Jyotir Linga. Astronomically, the festival is perfectly timed: the Pleiades (Karthigai) cluster rises at its highest point in the night sky precisely on this full moon.
The astronomical precision of Karthigai Deepam: The festival requires three simultaneous conditions — full moon (Pournami), the Tamil month of Karthigai, and the Moon in the Karthigai Nakshatra. Ancient Tamil astronomers who could calculate all three converging was a remarkable feat of early calendar science.
Karthigai in the Panchangam
In daily Tamil Panchangam use, Karthigai Nakshatra recurs every 27 days as the Moon completes its orbit. Days when the Moon is in Karthigai are considered auspicious for fire rituals (Agni-related pujas), temple visits to Murugan shrines, and new beginnings. It is the Nakshatra of energy, courage, and purification by fire.
| Attribute | Detail |
|---|---|
| Position | 6th Nakshatra (26°40′ Aries to 10°00′ Taurus, sidereal) |
| Western Equivalent | Pleiades star cluster (Taurus) |
| Ruling Planet | Sun (Surya) |
| Presiding Deity | Agni (fire god); associated with Murugan |
| Symbol | A razor or flame |
| Quality (Guna) | Rajas (active, passionate) |
| Tamil Month | Karthigai (November–December) |
| Key Festival | Karthigai Deepam (full moon of Karthigai) |
| Distance from Earth | ~444 light-years |
| Best Viewing Season | November to April, Tamil Nadu skies |
The 27 Nakshatras — Coming in This Series
Karthigai is just the first in our Nakshatra series. Over the coming weeks, we will cover all 27 star-mansions — their astronomy, mythology, ruling planets, and significance in the Tamil Panchangam. Each one is a window into how ancient Tamil astronomers organised the entire night sky into a living calendar.
Next in the series: Rohini — the red star Aldebaran, the Moon's favourite mansion, and why it governs agriculture and abundance in Tamil tradition.