Ardra is the sixth nakshatra, from 66 degrees 40 minutes to 80 degrees of the sidereal zodiac in Gemini, in the region of the bright star Betelgeuse. Its Vimshottari ruler is Rahu, the Moon's ascending node; its presiding deity is Rudra, the storm-god and fierce form of Shiva; and its symbol is a teardrop or, in some lists, a diamond. The name means moist or wet. Jyotisha reads Ardra through Rudra's storm energy, upheaval, destruction that clears the ground, the tear that both grieves and renews, and classes it as Manushya gana. It is treated as one of the more turbulent mansions, the fresh cleansing of the storm following the seeking of Mrigashira. These attributions are traditional; the associated star, Betelgeuse, is the red supergiant marking Orion's shoulder.
Ardra's padas run through Cancer, Leo, Virgo and Libra. Betelgeuse is a red supergiant near the end of its life, and modern astronomers regard it as a plausible candidate to become visible as a supernova on a human timescale, though the event could still be a hundred thousand years off; this astrophysical instability has no bearing on the classical Rudra attribution but sits suggestively alongside a mansion already read as stormy and destructive. Ardra is also one of three nakshatras, together with Swati and Shatabhisha, ruled by Rahu in the Vimshottari sequence, and jyotisha commonly treats all three as sharing a note of the unconventional and the disruptive that follows the shadow planet's rulership regardless of the mansion's own separate deity and symbol.