Śakata

Authors: Susanne M Hoffmann

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Hyades star cluster (CC BY Roberto Mura)

Cart in the Hyades (CC BY B. S. Shylaja)

Shakata, Rohiṇīśakaṭa , Rohiṇī (रोहिणी)'s Cart, is an Indian name for the Hyades in Taurus. Its age is unknown.

Concordance, Etymology, History

Variants

• Shakata
• Rohini Shakata
• Shakata Rohini

Hyades group is called Rohini Shakata - the cart of Rohini. When the moon or any planet is within the V-shape of Hyades it is called Rohini shakata bheda (cutting Rohini's cart).

Kugel Globe: Taurus with a deity in a cart, overlapping the area of modern Taurus+Auriga (drawing by SMH 2024)

The only historical image preserved in astronomical context is the engraving on the Kugel Globe.

Origin of Constellation

The word śakaṭa means a cart. Hyades is referred to as Rohiṅī śakaṭa  - the cart of Rohiṅī. We find references to the cart of Rohiṅī (Aldebaran) in many Sanskrit texts. Rohiṅī is one of the 27 stars used extensively as a nakṣatra. The V-shaped pattern of Hyades is the śakaṭa.

However, the context where this name appears provides the clue. All texts have a chapter called grahayuti, the mutual conjunctions of moon and planets and / or with the stars. The procedures are provided to compute the event. In this context, śakaṭa- bheda is a special event. The word literally means cutting through the cart or breaking the cart. This essentially means that the moon / planet will be within the V-shape of Hyades. The earliest text to mention this śiṣydhīvriddhidatantra of Lalla (Chatterjee, 1981). It provides the condition for the event (śakaṭa-bheda) as the dhruvaka 1^R|16°|40’ and śara 4°|30’ S. These can be approximated as ecliptic longitude and latitude for small values of the latitude.  1R refers to the unit of 30°, R for Rāśi, the zodiacal sign. Therefore, dhruvaka is 46° |40’

Stellarium image of the Hyades region for the year 443CE

The Stellarium image of the Hyades region for the year 443CE. The date of śiṣydhīvriddhidatantra is assigned to be 8^th century (Chattarjee, 1981). The precise date of the text is not known preventing the application of precession correction. There is also a clue that he was using a reference which was probably 400 years earlier to him, justifying the depiction shown. The fine tuning of the ecliptic longitude has been used so as to match with that given in the text. This clearly shows the marker within the V shape of the Hyades.

The other texts which specifically refer to this event are Grahalāghava, (16^th century) by Ganeśa Daivajnya (Balachandra Rao and Padmaja, 2008) and Samanta Chandrashekhara in Siddhānta Darpaṅa (19^th century) (Upadhyaya, online source). The latter states that the event is decided by the maximum value of śara possible for the planets, which is the same as the orbital inclination. According to him the event śakaṭa-bheda is possible for only budha and śukra (Mercury and Venus), rarely possible for śani (with parama śara as 2°|29’) and impossible for mangala (Mars).

The drawing depicting the cart of Rohiṅī (drawn by B S Shylaja) for a sky theatre show in the planetarium.

Cultural Significance

Rohini Nakshatra is the bright star of the constellation of Taurus identified with the bright star Aldebaran.

Classical texts have a chapter on conjunctions of moon and planets with stars ; the details on calculations for the possibility of the moon/planet passing within the V of Hyades (shakata bheda ) are provided. Rohini Shakata Bheda is a rare, astronomical phenomenon where a planet, often Saturn or Mars, passes through or breaks this "wagon" formation.

Transfer and Transformation of the Constellation

• 
  Chariot on Kugel Globe (CC BY "private collection of Nicolas and Alexis Kugel", Paris).
• 
  Kugel Globe: Taurus with a deity in a cart, overlapping the area of modern Taurus+Auriga (drawing by SMH 2024)
• 
  Cart in the Hyades (CC BY B. S. Shylaja)
• 
  Rohiṇī (रोहिणी) nakshatra, 10th century temple
• 
  Rohiṇī (रोहिणी) as reconstructed by Jones (1720)

Religion/ Tales/ Mythology

In Hindu tradition, Rohini Shakata Bheda is linked to stories like the, a, warning by Shani (Saturn) to Dashrath regarding the dire consequences of this crossing. A Rohini Shakata Bheda by Venus occurred in summer 2025, for example.

References

• References (general)