Introduction to Jyotish Online Course

Session 1 Part 2b

Master Teacher David Bruce Hughes

Babaji: We're going to start talking about astronomical concepts. As I said, astronomy is fundamental to Vedic astrology. An astrological chart is nothing but a picture of the sky at the time of a person’s birth. So to understand what is represented in the astrological chart, we need to understand how the different astronomical concepts are shown in the astrology chart. And that will help you visualize what the chart is trying to tell you or what the chart is trying to show you about the sky at the time of the person’s birth.

So again, I’ve started with the Jantar Mantar. We don’t need telescopes. We don’t need computers. We don't need anything technological to do Vedic astrology. The ancient astrologers did very fine work with nothing but instruments like this. Why? How could they do that? Because they understood the purpose, or I should say they understood the mechanism of how the planets in the sky work. And so they had a conception, they had an image in their minds that when they saw the chart it would remind them of how the sky actually looked at that time. OK, how is this done? Well, it turns out astronomy is a very highly developed subject in Vedic culture, and with instruments like Jantar Mantar, we can only imagine what instruments that must have existed that are now ruined, and we can’t see how they worked. Actually, the Jantar Mantar itself required additional instruments, especially you see these rails on the side? And you see these rings on both sides? Well there were additional instruments that were placed on those things, mirrors and so on that would reflect the light of certain stars. And then people would go up this central stairway or they would go up this side stairways and put other instruments on the scales on the side, and that's how they would measure the actual position of the stars and planets. They could make a distinction of just a fraction of a minute of arc, a few seconds of time in the position of the planets or the moon or stars or sun. Those instruments were kept, you see these doors? The instruments were kept inside these chambers and they were brought out and placed on the different scales at night and used to make observations. It's not that this thing was just a piece of stone and people would try to, you know, sight along it or something like that. No, they had other pieces of metal, like similar to astrolabes or sextets and stuff like that. So it was a very developed technology.

However, their technology of astronomy and astrology was based on a geocentric conception. And now we go to the next slide, Geocentric conception of reality. Geocentric means centered on the earth. As you can see, in this drawing the earth is at the center. Here is Africa, here is Asia, here is India right here. Europe is up there, Australia is down here, Malaysia, China. So the earth is in the middle, and these bands around the outside are the different planets’ orbits. And then finally, all the way on the outside these are the different astrological constellations. There’s Gemini, Cancer, Taurus, Aries, and then Pisces would be here, it’s hard to see. This is a very old drawing, a very old manuscript. And here’s the moon over here. So we can see that the ancients had a view of reality that was centered on the earth. Well you might say they were ignorant, they didn’t know that the earth actually goes around the Sun. But that’s not true. If we read in the Vedas, it's mentioned specifically that the earth moves around the sun. So why is Vedic astronomy geocentric? Simply because that’s where we are located. We are not located on the Sun, we’re located on the earth. And when we make astronomical observations we’re doing it from the point of view of the surface of the earth. So it doesn't make any sense to calculate astronomy based on the Sun, or some other point. It makes sense to look at it from the point of view of the earth, because that's where we are.

So what does that mean? That means we have in Vedic astrology a set of coordinates that’s based on the surface of the earth, OK. Let's look at a drawing of the earth, it’s a cutaway view actually, of a sphere. It says here, reference surface is a sphere. So if we have a, let’s say we have a sphere, a ball, and then it has these lines inscribed in it. First is the equator that goes around the middle, the north pole, and the south pole is down here which you cannot see because it's on the back. And then we have the Greenwich Meridian. What is the Greenwich Meridian? Well, every coordinate system has a zero point. This is called the origin. In our coordinate system of position on the surface of the earth, the zero point is Greenwich, England. When the English were a very important government on the earth they declared, OK our observatory in Greenwich is the center of the world. Everything is measured compared to that. So they were a little arrogant, but oh well. So the Greenwich Meridian is zero degrees longitude. Longitude is the distance east and west along the equator. Each of these vertical lines is a line of longitude. Similarly, we also have latitude. Latitude is the distance from the equator. If the equator is zero degrees latitude, then there’s ten, twenty, thirty, forty, fifty, sixty, seventy, eighty, ninety degrees latitude is the north pole. Similarly, the Greenwich Meridian is zero degrees longitude. And from Greenwich, ten degrees west, twenty degrees west, thirty degrees west, or ten, twenty, thirty degrees, forty degrees east is longitude. Why is this important? Because we measure positions in the sky based on the positions on the earth. In other words, it's as if we took these lines measuring latitude and longitude from the surface of the earth, and we project them out into the sky. And we use the same coordinates to measure the position of a planet or star. Let's say there's a star here, p is the star. So we say OK, first of all, what is the angular distance from the Greenwich Meridian to the meridian to where the star is located? That's going to be the longitude, or the right ascension of the star. And then you say what is the latitude, or height of the star above the equator? And that is called the azimuth of the star, ok? Azimuth, a-z-i-m-u-t-h, azimuth.

Uddhava: The other was called?

Babaji: The right ascension, yeah. But really those are just the same as latitude and longitude, OK? Latitude and longitude become azimuth and right ascension in astronomy. And all it is, is the same grid projected straight up from the earth to the sky, OK? So that's called the polar equatorial coordinate system. Why am I telling you this? Because there's another one based on the ecliptic. And we’ll see that. So before we go on to that, there’s a few more features I would like to explain on this drawing. First of all, in astronomy, longitude is equivalent to time. Why? Lets say it’s midnight in Greenwich. OK, it’s midnight in Greenwich. And then there’s 360 degrees of longitude going all the way around the earth and coming back again. So that means every fifteen degrees of longitude is equal to one hour of time. If it’s midnight in Greenwich then it’s eleven o'clock here, it's ten o'clock over here, nine o'clock over here, and here's one o'clock in the morning, two o'clock in the morning, three o'clock in the morning, you see? The earth turns toward the east. It turns from the west toward the east. That's why the sun rises in the east, because the earth is turning in that direction. And it sets in the west, because then we're moving away from it in the evening. So at some point on the earth it's always midnight. At some point it's one o'clock, two o'clock, three o'clock, depending on the rotation on the earth. Therefore, time and longitude are equivalent. Every fifteen degrees of longitude is one hour of time, because 24 hours divided into 360 degrees gives you 15 degrees.

So we talked about how the astronomical coordinate system is a projection of the earth’s coordinate system into space. Now let’s look at a picture of that. Here’s the earth, and here’s the equator going around the middle of the earth. Here’s the north pole, here’s the south pole. Now, when we project these things out into space, we have a north celestial pole, the south celestial pole, and the celestial equator. Is everybody clear on that? I want you to be very clear on this because it’s very important to any kind of measurements. Now we have, besides the celestial equator, we have something else called an ecliptic. Well what the heck is that? The ecliptic, as you can see, is a circle that's different from the celestial equator. That's because the axis of the earth is inclined from its orbit by 23½ degrees. So the plain of the earth's orbit around the sun is 23½ degrees different from the celestial equator. That's 23½ degrees right there. OK, so when we see the Sun, the Moon, the planets, they all follow the ecliptic because that is the plain of the earths orbit or the plain of the solar system. And, that makes things a little complicated because now we have the celestial equator being a projection of the earth’s equator, and the celestial poles as projections of the earth’s poles; but the actual movements of the planets occur along this line called the ecliptic. OK, so we'll always see these two components of the position of any heavenly body: the right ascension, or the declination or azimuth which is nothing but longitude and latitude. Longitude is right ascension, and that’s also time. Latitude is also declination, or azimuth. I'm going over this again and again because I want to make sure it's totally clear.

Now the earth rotates around its axis once every day, and we arbitrarily divide a day into 24 hours. And actually this is Vedic, because the day in Vedic conception is to divided up into 24 horas. So we have this in Spanish also, hora. Hora means hour. So 24 hours which are also called bhuktis is Sanskrit. So when the earth rotates around its axis one time, that means the Sun is coming back into the same position over a particular place every twenty-four hours, approximately. It actually is a little bit different from that, and we'll get into that when we discuss sidereal time. All of these things have little exceptions. So then the earth revolves around the Sun in its orbit once every 365 days, 5 hours, 48 minutes and 46 seconds. Just to make it interesting, it's not exactly 365 days. And we'll also show the reasons for that. This is called a tropical year. There's also a sidereal year, just like there's a tropical day and a sidereal day. And we'll show you the difference as soon as we build up enough background so you can understand it.

Let's talk about the equinoxes. Here's a bigger picture in which the earth is smaller at the center. And here we see the north celestial pole and the south celestial pole. This is the north pole of the solar system, and this is the south pole of the solar system. So here's the celestial equator, and here's the ecliptic twenty-three and a half degrees apart at their widest. But you see that there's a place where they cross; they cross here and here. This is called the vernal equinox, when the Sun is on the way north. And then when the Sun is on the way south and it crosses the celestial equator, this is called the autumnal equinox. And similarly, when the Sun is at its most southward point, 23.5 degrees south of the celestial equator, this is called the winter solstice. And when it's 23.5 degrees north of the equator it's called the summer solstice. So this is all because the axis of the earth is inclined to the axis of the solar system by 23.5 degrees.

Uddhava: This is every year right?

Babaji: Every year, right, right. In fact we actually, we measure our year by the equinoxes, not exactly by the number of days. And the reason for that is, the weather, the astrological patterns, the signs the Rasis, the Naksatras, all of this is determined with relation to the vernal equinox. The vernal equinox is a very important point. Actually all the equinoxes and solstices are very important. So when the Sun is in the north, it's summer in the northern hemisphere and winter in the southern hemisphere, like down in South America and Africa and Australia. When the Sun is in the south, it's winter in the northern hemisphere but it's summer in the southern hemisphere. So that's nice and confusing. Why is that? It's because when the sun is in the north, of course it shines more in the northern hemisphere. The days are longer, they get more sunshine, the Sun is higher in the sky so they get more energy, more radiation. And similarly, when the Sun is way south, in the northern countries it's very cold because there's very little sunshine. The days are very short, they don't get much radiant heat so that's winter. So the equinoxes and the solstices are the times of the year that mark the seasons, and of course the seasons determine the weather. And if you're involved in agriculture the weather is very important. So if you have a calendar that is based on the solstice you can make very accurate predictions regarding the weather, because the weather has yearly patterns according to the solstices and the equinoxes.

Now let’s look at some of the parts of the sky that are important in the Vedic chart. We're standing on the north pole and we're looking at the horizon. This is the horizon, and then we see here is the ecliptic. Remember the ecliptic is where all the planets’ orbits and where the Sun is also found. It's called the ecliptic because all the eclipses occur there. There's a part of the ecliptic that is ascending over the horizon. And guess what that's called, the Ascendent. And there's another part of the ecliptic that is descending over the horizon and that's called the Descendent.

Similarly, the part of the ecliptic that is at the lowest point below the horizon is called the Imam Coeli. And the part that's at the highest point above the horizon is called the Medium Coeli, the MC or the IC. You'll see these abbreviations in certain astrological charts. Then we have the Zenith and the Nadir. The point directly over head is called the Zenith, and the point of the sky that's directly under our feet is called the Nadir. So any place that we go on the earth the sky is going to have these different features. The Descendent is generally going to be in the western part of the sky, and the Ascendent is generally going to be in the eastern part of the sky. Similarly, the Imam Coeli is going to be in the north and the Medium Coeli is going to be south. The Zenith is always going to be straight up over head and the Nadir is always going to be right below our feet.

The Meridians, whether they are of a celestial longitude or earthly longitude, are always going to be great circles. Similarly, the celestial equator and the ecliptic are also great circles. What does that mean? That means they occupy the greatest amount of radius on the projection of the sky. We could also have a circle that cuts off this part of the sphere, of the sky, but that wouldn't be a great circle. It's only a great circle if it goes through the Zenith and the Nadir, through the north and the south point. And the center of the circle is identical with the center of the earth, that's a great circle. So we should know that all these are great circles, the meridians, the ecliptic, and the celestial equator. OK, so these are the parts of the anatomy of the sky. The planets move along the ecliptic, or actually this way, and they follow the ecliptic path, whereas the stars move parallel to the celestial equator. Why is that? Well because the earth rotates around its equator. And remember the equator is just the earth coordinates projected out on to the sky. So the stars appear to move from west to east in a circle around the celestial equator. The planets rather, whereas they follow the stars in their daily motion, over time they move on the ecliptic and they actually move backwards compared to the location of earth.

Uddhava: Only the planets?

Babaji: Only the planets, the planets and the Sun and the Moon. Well, in Vedic astronomy the Sun and Moon are also considered planets, Graha. That's why I like the word Graha, because in English, the Sun is a star, the Moon is a satellite. And what is Rahu and Ketu? They're just points you know, yeah. But in Vedic astrology they all come under the word Graha. So it makes it very simple. Because believe me, if you don't understand this stuff very clearly you're gonna be confused later in the course.

Uddhava: Is the earth wobble factor in Jyotish?

Babaji: The earth wobble is so tiny that it really doesn't make any difference in Jyotish.

Uddhava: What is wobble?

Babaji: The wobble is the wandering of the earth’s pole. I mean unless it wobbles so much that it changes the rotation of the earth. Right now the wobble is much less than one second of arc, which really doesn't make a whole lot of difference.

Uddhava: Well the ecliptic is so important because this is the only space in the sky we can actually observe, because we need the Suns light which goes past the earth to see. Is that right?

Babaji: Not exactly. I'm not quite sure what you're getting at here. Of course the planets only shine by reflected light. The sun is the only body that actually emits light. So the Sun is really special.

Uddhava: Is the relationship between ecliptic as a celestial sine function? Does it also oscillate?

Babaji: It does over a period of over 27,500 years. But we don't need to be concerned with that on a daily basis for astrology readings.

Uddhava: Why did you say that in this picture we're in the north pole?

Babaji: Because the distance between the horizon and the ecliptic is twenty-three and a half degrees. If you're on another part of the planet then both the celestial equator and the ecliptic are turned. The fact that the celestial equator is identical with the horizon here indicates that the point of view of the observer is from the north pole. The north pole and the south pole are the only places on the earth where the celestial equator and the horizon are identical. Any place else on the earth the celestial equator will have some inclination. And of course, the difference between the ecliptic and the celestial equator will always be twenty-three and a half degrees wherever you are.

Uddhava: I am confused.

Babaji: Yeah it's very confusing, that's why I asked if there's any questions. Remember, the celestial equator is simply a projection of the earths equator out into space. Whereas the ecliptic, here's the ecliptic, is actually the plane of the solar system where the earths orbit and the other planets orbits exist, OK. So then, let's say we're standing on the north pole. So straight up over our head is going to be the north celestial pole. And if we're standing on the north pole and we look out at the horizon, where is the horizon gonna be? Straight out here right? So the horizon and the celestial equator are gonna be parallel. It's the only place on earth where that is so. So let's take the most extreme other example. Lets say we're standing on the equator. So now if we look straight up, what are we gonna see? The celestial equator; And the north pole is gonna be on the horizon. See the Descendent and the Ascendent are on the horizon. So this picture assumes that the horizon and the celestial equator are identical. The Descendent is where the ecliptic and the horizon meet. The Ascendent is where the ecliptic and the horizon meet. The ecliptic and the horizon, not the ecliptic and the celestial equator. The ecliptic and the horizon.

Uddhava: What horizon?

Babaji: Whatever horizon you're at, wherever you are. But like I said, this doesn't show a distinction between the horizon and the celestial equator, therefore this assumes that you're standing on the north pole. Florian says, when we see signs rising in the east is that the Ascendent? Yes, that's exactly what the ascendent is. When a sign rises in the... remember all the signs are along the ecliptic. We'll get into that when we talk about the Rasis next.

Uddhava: The signs or the Grahas?

Babaji: The signs and the Grahas. OK, if we were on the equator, this whole thing would be turned ninety degrees. No, the zenith is still on the top, but then this circle would become the horizon and the celestial equator would be straight up and down. Remember when we looked here. If you're standing on the equator, the celestial equator will be overhead, and the north pole will be on the horizon. Because the horizon is always ninety degrees from where you are standing.

Uddhava: I understand that and where would be the Ascendent?

Babaji: The Ascendent would be at the same place, where the ecliptic crosses the horizon. The celestial equator, the ecliptic and the horizon are always great circles.

Uddhava: In that case you would see the planets going above us like that?

Babaji: Yes that's right. On the north pole we would see the planets orbits inclined twenty-three and a half degrees to the horizon. On the equator we would see the planets orbits inclined twenty-three and a half degrees to the Zenith. Because the celestial equator would be directly overhead. OK, all three are great circles, the horizon, the celestial equator and the ecliptic.