Grahas (ग्रहाः)

This article needs editing. Add and improvise the content from reliable sources.

Grahas in the Vedic literature

The Rgveda refers to five planets as deities, out of which it mentions Brhaspati (Jupiter) and Vena (Venus) by name.

अमी ये पञ्चोक्षणो मध्ये तस्थुर्महो दिवः । देवत्रा नु प्रवाच्यं सध्रीचीना नि वावृतुर्वित्तं मे अस्य रोदसी ॥१०॥ Rg. 1.105.10

बृहस्पतिः प्रथमं जायमानो महो ज्योतिषः परमे व्योमन् । सप्तास्यस्तुविजातो रवेण वि सप्तरश्मिरधमत्तमांसि ॥४॥ Rg. 4.50.4

अयं वेनश्चोदयत्पृश्निगर्भा ज्योतिर्जरायू रजसो विमाने । इममपां संगमे सूर्यस्य शिशुं न विप्रा मतिभी रिहन्ति ॥१॥ Rg. 10.123.1

अथ मन्थिनं गृह्णाति । अयं वेनश्चोदयत्पृश्निगर्भा ज्योतिर्जरायू रजसो विमाने इममपां संगमे सूर्यस्य शिशुं न विप्रा मतिभी रिहन्ति उपयामगृहीतोऽसि मर्काय त्वेति - ४.२.१.[१०] Shat. brah. 4.2.1

Shani (Saturn), Rahu (Moon's ascending node), and Ketu (Moon's descending node) are mentioned in the Maitrayani Upanishad 7.6

शनिराहुकेतूरगरक्षोयक्षनरविहगशरभेभादयोऽधस्तादुद्यन्ति तपन्ति वर्षन्ति स्तुवन्ति पुनर्विशन्ति अन्तर्विवरेणेक्षन्ति यः प्राज्ञो विधरणः सर्वान्तरोऽक्षरः शुद्धः पूतः भान्तः क्षान्तः शान्तः ॥ ७.६॥ Mait. Upan. 7.6

It also mentions 34 lights which, in all probability, are the Sun, the Moon, the 5 planets and the 27 nakshatras (Rg 10.55.3)

आ रोदसी अपृणादोत मध्यं पञ्च देवाँ ऋतुशः सप्तसप्त । चतुस्त्रिंशता पुरुधा वि चष्टे सरूपेण ज्योतिषा विव्रतेन ॥३॥ Rg. 10.55.3.

The Rgveda describes the Sun as the sole light-giver of the universe, the cause of the seasons, the controller and the lord of the world.

एक एवाग्निर्बहुधा समिद्ध एकः सूर्यो विश्वमनु प्रभूतः । एकैवोषाः सर्वमिदं वि भात्येकं वा इदं वि बभूव सर्वम् ॥२॥ Rg. 8.58.2

त्रीणि जाना परि भूषन्त्यस्य समुद्र एकं दिव्येकमप्सु । पूर्वामनु प्र दिशं पार्थिवानामृतून्प्रशासद्वि दधावनुष्ठु ॥३॥ Rg. 1.95.3

सनेमि चक्रमजरं वि वावृत उत्तानायां दश युक्ता वहन्ति । सूर्यस्य चक्षू रजसैत्यावृतं तस्मिन्नार्पिता भुवनानि विश्वा ॥१४॥ Rg. 1.164.14

Aitareya brahmana 2.7 describes Sun as the cause of the wind. The Moon is called Surya-rashmi ie. one which shines by sunlight (Taittiriya Samhita 3.4.7.1)

ऋताषाड् ऋतधामाग्निर् गन्धर्वस् तस्यौषधयो ऽप्सरस ऊर्जो नाम स इदम् ब्रह्म क्षत्रम् पातु ता इदम् ब्रह्म क्षत्रम् पान्तु तस्मै स्वाहा ताभ्यः स्वाहा सꣳहितो विश्वसामा सूर्यो गन्धर्वस् तस्य मरीचयो ऽप्सरस आयुवः सुषुम्नः सूर्यरश्मिश् चन्द्रमा गन्धर्वस् तस्य नक्षत्राण्य् अप्सरसो बेकुरयः । भुज्युः सुपर्णो यज्ञो गन्धर्वस् तस्य दक्षिणा अप्सरस स्तवाः प्रजापतिर् विश्वकर्मा मनः Tait. Samh. 3.4.7.1.

According to the Taittiriya brahmana 3.1.1, "Jupiter when born was first visible in the nakshatra Tishya (Pushya).

बृहस्पतिः प्रथमं जायमानः । तिष्यं नक्षत्रमभि संबभूव ।

Evolution in the study of the Grahas

The study of the five planets, that were known in the vedic period, came to be included within the scope of astronomy in the post-vedic period. And astronomy began to be studied as a science for its own sake outgrowing its original purpose of providing a calendar for the performance of Vedic yajnas.

The various facets related to the grahas that were studied were:

• their synodic motion
• the times of their first and last visibility
• the duration of their appearance and disappearance
• the distance from the Sun at the time of their first and last visibility
• the times of their retrograde motion
• the distances from the Sun at the times of their becoming retrograde and re-retrograde

It also studied the motion of the planets in various zodiacal signs under different velocities called gatis (viz. very fast, fast, mean, slow, very slow, retrograde, very retrograde, and re-retrograde) along their varying paths called vithis.

The synodic motion of a planet, called grahachara, was elaborately recorded in the astrological works particularly the samhitas, the earlier works of the Jainas, the earlier puranas, and the earlier siddhantas such as the Vasishthasiddhanta and the Paulishasiddhanta. Analysis of these records led to the evolution of a few crude methods and empirical formulae to get the longitudes of the planets. Later, a systematic theory was established giving rise to the astronomy of the later Siddhantas.

The synodic motion of the planets and the empirical formulae for knowing the positions of the planets Jupiter and Saturn were described in the Vasishthasiddhanta which is the earliest of the astronomical works written in the post-vedic period. This is known through the summary of the Vasishthasiddhanta available in the Panchasiddhantika of Varahamihira.

The motion of the planets, visibility of the Moon and eclipses are dealt with in the Paulishasiddhanta also. In the treatment of the planetary motion, it gives the distances from the Sun at which the planets rise or set heliacally and become retrograde and re-retrograde. However, Paulisha's treatment of the visibility of the planets and the eclipses is considered to be very approximate.

A synodic year is the time it takes for a planet-sun alignment to reoccur.

The synodic periods (in days) of the planets according to Vasishtha, Paulisha, Aryabhata, Ptolemy and the modern astronomers are as follows:

Synodic periods in days

Planet	Vasishtha	Paulisha	Aryabhata	Ptolemy	Modern
Mars	779.955	799.978	779.92	779.943	779.936
Mercury	115.879	115.875	115.87	115.879	115.877
Jupiter	398.889	398.885	398.889	398.886	398.884
Venus	583.909	583.906	583.89	584.000	583.921
Saturn	378.1	378.110	378.08	378.093	378.092