ASTROLOGY – Heliocentric or Geocentric Model


In this post, we are going to analyze about the popular myth that Astrology supports geocentric theory, i.e earth is the center of the solar system with Sun and other planets revolving around earth. With this single mis-interpretation, many come to the conclusion that Astrology is not scientific. I would like to stress the point from the earlier post that Astrology is the study of planetary influence on human life on earth. Hence earth is taken as the point of observation. This has lead to the myth that astrology supports geocentric theory. As an student of astrology I strongly believe that the ancient seers on India who authored Astrology, who could calculate planetary positions for past, present and future, who had divine knowledge; certainly could have known that planets including earth revolved around the Sun. But science demands reason, logic and evidence. This article is dedicated to all those science lovers who are willing to analyze, think logically and decide for themselves.

Let us look deep into the horoscope and try to figure out what was the understanding, our ancient Astrologer had about the solar system. Horoscope is nothing but the position of planets as seen from Earth(which is why you see Earth is  marked in the center of the horoscope shown below) at a particular time mapped in a frame of reference called Zodiac. For info on the Zodiac, please refer the previous post. Earth is the point of observation or the point where humans are located, hence it is completely logical that for the study of Planetary influence on human life, Earth is taken to be the center point of the horoscope, but that itself doesn’t mean that other planets are revolving around the Earth.


The definition of Geocentric model say that the “Earth is the center of the universe, and that all other objects orbit around it. The stars, sun, and planets appear to revolve around the Earth each day”. Firstly, in Astrology Earth is the center of observation and not the center of universe. Secondly none of the planets in a horoscope complete one revolution around the zodiac in a single day. Let us take Sun for example, if Sun was revolving around earth, by observation through naked eye we know that Sun travels around the east to west in half a day and come back to eastern horizon the next day morning. Hence Sun should take one day to travel around the earth, which is what Geocentric theory says. But in a horoscope as illustrated above(Click on image to enlarge) casted for two different dates, that is not true, for Sun to come back to the same point in Zodiac, it take one year. Hence it is obvious that Astrologer were aware of the fact that either Earth takes one year to revolve around the Sun or Sun takes one year to revolve around the earth, which we haven’t concluded yet. In fact none of the planets in a horoscope completes a full round in one day.

The above table compares the period of revolution of planets around Sun and in a zodiac as observed from earth which is the horoscope. As you can see that for outer orbit planets(compared to earth) the period of revolution around Sun and in horoscope matches exactly. For inner orbit planets there is a slight deviation which we will see later. The fourth column is very interesting. All planets in horoscope moves in the clockwise direction, but while in retrograde motion, they move in the reverse direction for certain period of time and then continue to move in their usual clockwise direction. You can imagine retrograde motion to an overtaking car, while overtaking with respect to the speeding car the slower car appears to move backward. In a circular/elliptical revolution, if for example Saturn were to revolve around Earth, there is no possibility of retrograde motion however elliptical the path may be. Saturn could be seen moving slower or faster at apogee and perigee but never in the reverse direction. Retrograde motion is possible only when there is a relative motion between two objects revolving around the third object, which proves beyond any doubt that Astrology doesn’t fit into Geocentric theory. It is interesting to note that only Sun and Moon doesn’t have retrograde motion as seen from Earth, because one is revolving around the other object.

Outer orbit planets(Saturn, Jupiter, Mars) have retrograde motion once in year when they are exactly opposite to Sun in the horoscope, which clearly shows that they are revolving around the Sun. Recalling the fact that Earth is in the center of the horoscope, when Saturn is opposite to Sun in the horoscope means; Sun, Earth and Saturn line up in a straight line. We also know that the outer orbit planets takes longer time to revolve around the Sun. Hence when Earth which is moving faster compared to the outer orbit planet, overtakes Saturn momentarily Saturn appears to retrogate(move backward) as seen from Earth.

Let us come to Mercury and Venus. Astrology calls these planets as inferior orbit planets or inner orbit planets. If you take a horoscope for any point in time, we can always notice that Mercury is within 60 degrees from that of Sun and Venus is with-in 90 degrees from Sun. Also, if we observe the position of Mercury, Venus and Sun for different date and time in a horoscope, we can observe that Mercury and Venus are moving to and forth across the Sun. The too and forth movement across the Sun clearly indicates that Mercury and Venus are revolving around the Sun. That is the reason why as seen from earth(Column-3), the period of revolution of Mecury and Venus is approximately 1 year coinciding with Sun’s movement. If I am able to understand this, I don’t believe that our super intelligent Astrologers couldn’t.

Last and interesting is our Moon. Moon can be understood to be the closest object to earth by it mere size as seen from Earth. Moon doesn’t have retrograde motion, hence it can’t be an outer orbit planet. Moon doesn’t go too & forth across Sun, hence it can’t be an inner orbit planet. Moon is the fastest moving object in the horoscope. Moon revolving around earth can be inferred from the fact that Lunar and Solar eclipse occur within a gap of 15 days, i.e for Moon to come from behind the Earth to between earth and Sun it takes 15 days, and for one complete revolution around earth take 30 days as can be seen in the horoscope.

Now we know that Earth has a relative motion and to calculate the position of a particular planet in future, you need to know, not only the motion of the other planet but also that of earth. Observing Sun and Moons movement from Earth is straight forward, because we are dealing with bilateral movement of two objects (Sun-Earth, Moon-Earth). But when dealing with Mecury, Venus, Mars, Jupiter and Venus, we are observing the movement of two objects (eg Mercury revolving around Sun) from a third object which is Earth, hence the complexity of calculations increases, since for calculating the movement of Mercury(as seen from earth), the movement of earth should also be taken into consideration. Our Astrologers have mastered all these movements and were able to calculate the position of planets as seen from earth for any point of time in past, present and future. How were they able to do this, without a telescope or any other equipment, is it possible without deep understanding of the Solar system? Whether to call it mystic science or divine knowledge is up to you.

To summarize, astrology perfectly fits into the heliocentric model of Solar system. Horoscope focuses movement of all objects with reference to Earth, incorporating the knowledge of movement of planets around Sun including that of Earth.

– Written by Saravana Kumar G


Poll: What is your opinion on Astrology?

Sun Sign Vs Moon Sign Vs Rising Sign

Have you ever been wondered why astrological prediction on daily newspaper based on Sun and Moon sign are too general and not applicable to you many times? To know the reason you need to understand the difference between Sun Sign, Moon Sign and Rising Sign.

Sun Sign: Sun sign is the sign (or Constellation) in which sun can be seen from the earth at any point of time. Since sun will be seen in same constellation for ~30 days, any two people born within 30 days of sun transit between constellations (Sun will be in same position, since earth is moving around the sun we will be observing sun transit) will have same sun sign. Let me explain with an example, everyone knows that earth takes one year to complete one revolution around the sun. Since our point of observation is from earth, sun will be seen in 12 different constellations during 12 months.


If you look at the above chart (Horoscope generated for Apr 10th 2014 7PM, Chennai) Sun is Pieces constellation (Sign – 12).


Look at the chart above which is generated for May 10th 2014 7PM Chennai, Sun is at Aries constellation (Sign -1).


Now look at the chart above which is generated for Apr 10th 2015 7PM, Chennai, Sun is again in pieces constellation (Sign – 12). From the above three chart one can logically understand that viewing from earth sun can be seen in each constellations for ~30 days in a year and will be seen on same constellation again exactly after one year.

Moon Sign: Moon sign is the sign (constellation) in which moon seen from the earth at any point of time. Moon takes ~28 days to complete one revolution around the earth, so moon will be viewed in same constellation for ~2.3 days. Any two people born between ~2.3 days between moon transitions will have same moon sign.

Rising Sign (Ascendant): Ascendant sign is eastern point of the sign (Constellation) viewed from the earth at any point of time. Earth takes 24 hours to complete its self revolution, so eastern point of the sign viewed from earth will vary for every ~2 hours (24 hours/12 Constellations). From this it is logical that rising sign is depend of time of birth of the person and hence astrologers give much importance to rising sign in predicting life events of individuals. Next logical question that arise in our mind is why our ancestors choose sign that rises on eastern point as rising sign? Think what you see every day in the east. Will you able to relate?

In summary Sun Sign will be same for all born on same month, Moon Sign will be same for all born on same day where as rising sign will be unique based on individuals time of birth. Let me explain with a analogy,  Sun Sign & Moon Sign predictions are like taking Paracetamol for fever, it will work out at times if it is general ailment, whereas Rising Sign prediction are like taking antibiotic based on doctor’s complete analysis of your body which will work for sure. Now I will leave it to you to conclude by yourself which basis of prediction will be more accurate.

–          Written by Elango Annamalai and Muthu Vijayan Elango

Zodiac – Frame of Reference in Astrology

Astrology is a mystic science, well it will continue to be until science become advanced enough to decode the mystic formulas. Astrology is not completely mystic by today’s science; we can call it 50% science and 50% mystic. We are going to analyze about the 50% scientific part first and look at the mystic part later. The objective it to enlighten people who still believe astrology is 0% science. In this post we are going to see what a ZODIAC is.

A horoscope of a person is the position of planets at the time of the birth of the individual as observed from earth. The positions of planets are mapped in circular reference called Zodiac. As most of us know, Zodiac consists of 12 signs which are also called as constellations. Why did our ancestors choose this set of 12 signs or constellation to map the position of planets? What is special about the Zodiac? Well let us get deeper and logical.

To mark the position of an object, the foremost thing is a reference frame, i.e. the position of planet has to be marked against something, that something is the zodiac. Let us take three persons (A, B, C) standing in a line side by side. For person-A, person-B is standing to the left, but for person-C, person-B is standing to the right, from which we can understand that position is relative. Let us see one more example, For the person in London, at 1200 GMT, the sun is above his head, if he calls his friend in India at that time and ask for the position of sun, the friend in India would tell him, Sun is at the west, another friends in Singapore would tell him that he is having his dinner. Though the position of Sun is same at that point in time, the difference in observation is due to difference in location. If all three want to communicate on the same term, they need a common reference using which they can tell the same position where ever they are. Hope the need for a common reference frame is clear.

There is one more major hurdle when we thing about plotting position of planets on a piece of paper, planets are moving in a three dimensional space, how is it possible to map it in a two dimensional piece of paper? Asking this question is the key to further understanding. It is possible, as we do in a horoscope, because of one astronomical fact. The fact is that all the planets from mercury to Saturn including earth revolve around our Sun in the same plane. i.e. the path of earth around Sun and path of Jupiter around Sun lie in the same plane, so does is that of Mercury, Venus, Mars and Saturn.

Let me stress the point which was mentioned earlier, we are plotting the position of planets as observed from earth. We are talking about influence of planets on human life. Since we are on earth it is logical that the point of observation is earth. There is a wrong misconception that Astrology supports geocentric theory, logical answers to prove that our ancestors knew that all planets were revolving around the Sun will form the basis for the next article.

Let us come back to the reference frame. The properties of the reference frame should be that is should encompass our entire solar system and it should be big enough so that the position on planets observed with this reference should not change where ever we are located on earth. Zodiac is the one with all these qualities. You can imagine our solar system as circles(path of planets around Sun) with Sun as the center, Zodiac is the big circle around our solar system. Zodiac consist of 12 constellations (group of stars) each spanning 30 degrees (360 divided by 12). Each constellation has a unique set of stars forming a unique shape which help us to easily identify the constellation or sign.

The following amazing facts make the Zodiac the perfect frame of reference.

1) As mentioned earlier, the path of revolution of all planets around the sun lie in the same plane. Amazingly Zodiac also lies in the same plane.

2) We (our solar system) are located in the center of the Zodiac.

3)The diameter of the solar system is negligible when compared to the diameter of the Zodiac. As the size of earth and other planets are  a dot compared to the size of the Zodiac, the observation on the position of planets is same when viewed from any point on the earth.

Let me try to explain using an example. The chart shown aside is the horoscope for Singapore latitude on April 5th 2014, 4am, i.e. the position of the planets as seen from Singapore at that time and date.  Some of you might ask, can we use this map to locate the planets in sky, of course you can star gaze using this chart. To help you read the chart, you need to know some fundamental things. “As” in the chart means Ascendent-the eastern point at that point in time, in this case “As” falls on sign number 11. 180 degrees from there is the west which is sign 5. Starting from East moving anticlockwise is the part of the zodiac above us; i.e. sign-8 will be right above our head.

Tomorrow(05-Apr-2014) morning if you wake up early look at the eastern horizon right before sun rise, you can observe a brilliant white beautiful star like object, which is planet Venus. In the chart you see Venus is in the eastern horizon in Sign-11.  Look above your head (little bit towards western horizon), you can observe Saturn in dull white. Both are clearly visible to the naked eye. Little west to Saturn you need to concentrate little harder to observe our Mars in faint red color.

Each of the signs (boxes) are numbered from 1 to 12. Each sign is a constellation. Sign-11 is Aquarius. We say Venus is in Aquarius at that time because we see Venus in the background of Aquarius. Similarly we say Jupiter is in Gemini (Sgin-3) because we see Jupiter in the background of Gemini. Hence all the positions we say are with respect to observation from earth, because we are talking about the influence of planets on human life on earth. From where ever we are on earth, we can observer Venus in the constellation of Aquarius and similarly all planets will be seen at the same sign where ever we are on earth, only Ascendant (AS) will change depending on our location. Amazing right, do you think our ancestors chose Zodiac as the reference frame with-out knowing all these fact.

Written by Saravana Kumar G