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Indian Astronomy: Part 2

Uttarayana and Dakshinayana


The move­ment of the sun along the eclip­tic from its most norther­ly dec­li­na­tion of +23.5 ° to its most souther­ly dec­li­na­tion of ‑23.5 ° is called the Dak­shi­nayana, or the south­ern move­ment of the sun. (sum­mer sol­stice to win­ter sol­stice)

The move­ment of the sun along the eclip­tic from its most souther­ly dec­li­na­tion of ‑23.5 °to its most norther­ly dec­li­na­tion of +23.5 ° is called Uttarayana, or the north­ern move­ment of the sun. (win­ter sol­stice to sum­mer sol­stice)

Fig. 13.1 – Uttarayana and Dak­shi­naya

Uttarayana and Dak­shi­nayana can be observed from the posi­tion of the sun­rise on the hori­zon on dif­fer­ent days of the year.

Fig. 13.2 – Sun­rise on dif­fer­ent days of the year

Rashis and nakshatras

The Zodi­ac or Rashi chakra and the naksha­tras are the pro­jec­tion of the dis­tant stars, which appear fixed with respect to the earth, onto the eclip­tic.

Fig. 14 – Rashis or Zodi­ac con­stel­la­tions pro­ject­ed onto the eclip­tic

The rashis divide the eclip­tic of 360° into 12 regions of 30° . The sun spends about a month in each rashi, com­plet­ing 360° in one year. Hence, the rashis can also be looked at as solar con­stel­la­tions.

The 12 rashis are giv­en below.

The naksha­tras divide the eclip­tic of 360° into 27 regions of 13° 20’. The moon spends one day in each naksha­tra, com­plet­ing 360° of the zodi­ac in 27 days, which is the lunar month (side­re­al*). Hence, the naksha­tras can also be looked at as lunar con­stel­la­tions.

Each naksha­tra is fur­ther divid­ed into 4 padas (quar­ter) 3° 20’ each. Thus there are 27 * 4 = 108 padas.

The 27 naksha­tras are giv­en below.

* There are two ways the lunar month is reck­oned : side­re­al and syn­od­ic. We will look at it in Part 2 of this arti­cle.

Fig. 15 – Rashis and naksha­tras

Orientation to the Galactic center

In Vedic astron­o­my, the rashi chakra is ori­ent­ed to the cen­ter of our galaxy, the Milky Way. The light from the galac­tic cen­ter comes to the earth through the fixed stars of the con­stel­la­tion Sagit­tar­ius, Dhanu.

In the rashi chakra, the galac­tic cen­ter is locat­ed in the ear­ly por­tion of Sagit­tar­ius. The naksha­tra Moola, mean­ing “root” or “source” sug­gests that it is the first of the series of naksha­tras on a cos­mic lev­el. It marks the first 13 ° 20′ of Sagit­tar­ius, in the mid­dle of which (6 ° 40′) is locat­ed the galac­tic cen­ter.

The pre­vi­ous naksha­tra is called Jyesh­ta, mean­ing “the eldest” which marks the end of Scor­pius. This shows that the ancients knew of the galac­tic cen­ter and named their con­stel­la­tions in such a way as to acknowl­edge it as the begin­ning.

Mod­ern astron­o­my con­firms this fact. Astronomers have dis­cov­ered that the galac­tic cen­ter is an intense radio source known as Sagit­tar­ius A*. It lies in the direc­tion of Sagit­tar­ius con­stel­la­tion, near the bor­der with Scor­pius (Fig. 18). Sagit­tar­ius A* is the most plau­si­ble can­di­date for the loca­tion of the super­mas­sive black hole at the cen­tre of our galaxy. (Fig. 19)

The Milky Way has 2 major arms and a num­ber of minor arms. One of the minor arms, known as the Ori­on Arm, con­tains the sun and the solar sys­tem. The Ori­on arm is locat­ed between two big­ger arms, Perseus (major arm) and Sagit­tar­ius. The sun is at a dis­tance of 26,000 light-years from the galac­tic cen­ter. (Fig. 15)

The Milky Way galaxy can be observed from the earth as a beau­ti­ful stretch, because the plane of the solar sys­tem (eclip­tic) is inclined at an angle of 60° to the galac­tic plane. (As shown in Fig. 16)

Fig. 15 – The loca­tion of our solar sys­tem in the Milky Way

Fig. 16 – Plane of the solar sys­tem (plane of eclip­tic) and galac­tic plane

Fig. 17 – Milky Way galaxy as viewed from the Earth

Fig. 18 – Galac­tic cen­ter – between Sagit­tar­ius and Scor­pio

Fig. 19 – Sagit­tar­ius A* at galac­tic cen­ter

The phases of the moon and thithi

Phas­es of the moon occur as a result of the posi­tion of the moon at dif­fer­ent points in its orbit around the earth. What we refer to as phase is the part of the moon’s sur­face illu­mined by the sun, as seen from the earth. This is shown in Fig. 20.

Fig. 20 – Thithis of the moon

The wax­ing phase is called Shuk­la pak­sha and the wan­ing phase is called Krish­na pak­sha.

A thithi is 12°movement of the moon with respect to the sun in the rashi chakra.

A thithi is a lunar day. There are 15 thithis in the Shuk­la pak­sha and 15 thithis in the Krish­na pak­sha.


Hence, 30 x 12°= 360° . The moon tra­vers­es the rashi chakra in 30 lunar days or thithis.

1.Pratipada

2.Dwitiya

3.Tritiya

4.Chaturthi

5.Panchami

6.Shashti

7.Saptami

8.Ashtami (Half moon)

9.Navami

10.Dashami

11.Ekadashi

12.Dwadashi

13.Trayodashi

14.Chaturdashi

15.Purnima (Full Moon in Shuk­la pak­sha) or Amavasya (New Moon in Krish­na pak­sha)

Fig. 21 – Thithi – 12° move­ment of the moon with respect to the sun

Grahana – solar and lunar eclipse

The moon’s orbit path is not in line with the earth-sun orbit path. It is tilt­ed by 5°. The points of inter­sec­tion of the moon’s path and the sun’s path are called nodes. As the earth moves in its orbit, these nodes line up with the sun twice a year.

If the moon is between the sun and the earth, we get a solar eclipse, surya gra­hana.

If the earth is between the sun and the moon, we get a lunar eclipse, chan­dra gra­hana.

Total eclipses are pos­si­ble only because the sun and the moon appear to be of the same size from earth. While the sun is 400 times big­ger than the moon, it is also 400 times far­ther away.

Fig. 22 – Lunar nodes – inter­sec­tion of moon path and sun path

Fig. 23 – Solar eclipse

Fig. 23.1 – Solar eclipse as seen from the earth

Fig. 24 – Lunar eclipse

Fig. 24.1 – Lunar eclipse as seen from the earth

The Navagrahas

The pri­ma­ry celes­tial bod­ies in Vedic astron­o­my are the nav­a­gra­has – 7 plan­ets and 2 lunar nodes.

Since the orbits of all plan­ets are near­ly on the same plane as the eclip­tic, with only minor dif­fer­ences, the gra­has also tra­verse the rashi chakra.

The 7 plan­ets:

1) Surya (Sun)

2) Chan­dra (Moon)

3) Bud­ha (Mer­cury)

4) Shukra (Venus)

5) Man­gala (Mars)

6) Guru (Jupiter)

7) Shani (Sat­urn)

Lunar nodes:

8) Rahu (Ascend­ing node) ‑the node where lunar eclipse occurs

9) Ketu (Descend­ing node) – the node where solar eclipse occurs

Fig. 25 – Gra­has

Each gra­ha has its own speed and cor­re­spond­ing time peri­od of tra­vers­ing the rashi chakra.

For exam­ple, the sun cov­ers about 1° in 1 day. Thus, it tra­vers­es a rashi (30°) in about 30 days, which is one solar month. The sun goes through the entire rashi chakra (360°) in about 360 days, which is one solar year.

The moon cov­ers 1° in 1 3/4 hours. It tra­vers­es a rashi (30°) in 2 and 1/4 days. It com­pletes the entire rashi chakra in 27 and 1/3 days, which is also its peri­od of rev­o­lu­tion around the earth. This con­sti­tutes a lunar month.

Precession of the Equinoxes

The axis of the earth spins like a top, and its direc­tion moves from the North star, Polaris, to Vega. As a result, the equinox­es (which are the inter­sec­tion points of the eclip­tic and the celes­tial equa­tor) pre­cess slow­ly west­wards rel­a­tive to the fixed stars, com­plet­ing one rev­o­lu­tion in about 24,000 years (Accord­ing to Sri Yuk­tesh­war*).

*Sri Yuk­tesh­war Giri was the Guru of Parama­ham­sa Yoganan­da. His Guru was Lahiri Mahasaya, whose Guru was Kriya Baba­ji.

Fig. 26 – Pre­ces­sion of the equinox­es

Due to pre­ces­sion, the equinox­es have moved around the eclip­tic such that the back­ground con­stel­la­tion for the ver­nal point is now Pisces, and for the autum­nal point is now Vir­go.

Fig. 27 – Cur­rent posi­tions of the equinox­es (2007)

The basic con­cepts of astron­o­my have been explained. How astron­o­my is con­nect­ed to time­keep­ing will be the sub­ject of the fol­low­ing arti­cle.

Fur­ther Read­ing:

If you are a sky watch­er or sky pho­tog­ra­phy enthu­si­ast and look­ing at get­ting a bet­ter under­stand­ing of polar align­ment, do read here.

Ref­er­ences

Fig. 1 – By Tfr000 (talk) 20:06, 29 March 2012 (UTC) – Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=18893066

Fig. 2 – Plane of the eclip­tic tilt­ed on the earth’s celes­tial sphere

By Brad Freese, pub­lished on Mar 29, 2009

Fig. 3 – By Tfr000 (talk) 15:34, 15 June 2012 (UTC) – Own work, CC BY-SA 3.0,https://commons.wikimedia.org/w/index.php?curid=19907447

Fig. 5 and Fig. 6 – PE Robin­son, Pub­lished on Jan 14, 2013

Figs 8, 9 10, 11 – Kur­dis­tan Plan­e­tar­i­um, Pub­lished on Mar 15, 2011

Fig. 13.2 – P.E. Robin­son

Pub­lished on Feb 3, 2013

Astrol­o­gy of the Seers by David Fraw­ley

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