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Encyclopedia of Vedic Astrology: Planetary Transit: Transit of Nodes, Chapter X, Part – 10

Dr. Shanker Adawal

10.6 Eclipses

Part 1

10.6.1 Introduction: Astronomically, an eclipse is the interposition of a dark celestial body between a luminous one and the eye, or passing of a luminous body into a shadow of another body. In astrology. The Sun & the Moon are considered as luminous planet; although Sun is a star and the Moon a satellite of Erath. From the Earth, the Sun, with a diameter of 139200 KM, on an average is at a distance of about 15 Crore KM, while the Moon with a small diameter of 3476 KM is only at a distance of 3.8 Lakh KM. But when seen from Earth, the Sun & Moon appears to be of same size, because of their relative distances. An eclipse is an interesting and unique transit phenomenon in which the Earth & Moon during their transit, happens to come in one plane & line of sight with the Sun, obstructing the light of Sun. The solar eclipse always happens at new Moon when both the luminaries are conjunct with the either Node and the Moon is in between the Sun & the Earth. It comes on from the West and passes over Eastward. While a Lunar eclipse always happens on a full Moon day, when the two Luminaries are in exact opposition one posited with Rahu & the other with the Ketu, such that the Earth is in between the Sun & the Moon. It comes from the East and passes over Westward.

10.6.2 Causes: The Sun takes about 365.25 days to complete one apparent cycle of the zodiac, while the Moon takes 27.25 days to complete one cycle and another about two days to catch up the additional movement Sun makes during this period. Thus the Moon takes about 29.3 days to come to the same original longitude. Thus in a solar year, there are 12 positions of new Moon & Full Moon each. Had the planes of orbit of Moon around Earth and of Earth around Sun been in the same plane, there could have been an eclipse every New & full Moon. But it is not so. The Nodes, which are basically point of intersection of Earth’s orbit around the Sun and of Moon’s orbit around the Earth, play an important & decisive role in an eclipse to occur, as the luminaries at the time must be within 5 degree of the Nodes, which is also the angle between the two planes of the orbits under consideration. The angular distance of Moon or any other planet from the ecliptic towards North/ South is called the celestial latitude of the planet. When the Moon is on zero degree latitude, it is called Rahu (Northern Node) or Ketu (Southern Node). The Moon during its one revolution of about a month, crosses Rahu & Ketu once, but The Sun transits Rahu & Ketu only once each during its one year of revolution. If the Moon happens to be near Rahu/ Ketu, when the Sun is also near Rahu/ Ketu and the two planes of orbits are within 5 degree, an eclipse may occur. The ancients discovered the regularity or the recurrence of eclipses after a period of 18-2/3 years, which is also the cyclic period of one revolution of a Node in the zodiac.

10.6.3 Types of Eclipses: When the Earth comes in between the Sun & the Moon, casting its shadow on Moon, it is Lunar eclipse. If the shadow of the Earth covers the Moon completely, it is called Total Lunar Eclipse and if the shadow covers only a part of the Moon, it is called Partial Lunar Eclipse. Similarly when the Moon comes in between the Earth & the Sun, such that the small disc of Moon casts its shadow on the Sun, it is Solar eclipse. If the shadow of the disc of Moon being equal to or more than the disc of the Sun, it covers the Sun completely, which happens when the longitudes of Sun, Moon & either of the nodes are exactly the same, a Total Solar Eclipse occurs. If the Moon has just crossed the Node, but its center is still transiting over the Sun, it covers only a part of the Sun, a Partial Solar Eclipse may occur. A third case may be when the shadow of the disc of Moon may be shorter than the disc of the Sun, then the some part of the Sun around a circular dark circle may remain luminous, the resultant eclipse is known as Annular/ Kankan Solar eclipse. An eclipse is not visible from all the places on the Earth of same duration, type or intensity.


Dr. Shanker Adawal

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