The chart and the actual sky

Okay, I promised I'd bother you all with strange questions! Here it goes!

So, I'm reading the books I have on astrology, and trying to grasp the basic principles before moving into interpretation. Right now I am looking at the charts not to understand what they mean, but to understand how they work. And I am having some difficulties.

I know the chart is representation on how the heavens look in a certain moment from a geocentric point of view. But I confess I am having a hard time relating the 2D chart to the 3D sky... and no book that I have give good explanation on what exactly is the chart showing. It also seems to me that the charts should change according to latitude - the houses, I think? - but I cannot see this difference very clearly in the charts I have been looking at (both from S.H. and N.H.).

I live in the southern hemisphere, and I am specially interested in understanding this because I know adaptations have to be done, because most of tables of houses are made for the northern hemisphere. In the books they tell you to invert the signs when defining the ascendent for a southern hemisphere and I can't understand why. It's probably something simple my brain is not getting.

Anyways, I feel that I really need to understand the dynamics of the chart in order to not become so dependent on computer programs. Even if I decide not to cast a chart by hand, and I want to know where the information in the chart comes from. I want to be able to cast a chart, in order to understand the process.

I think I may be a bit anal retentive, lol!

I feel that it's no use for me to know how to interpret planets and aspects if I don't even know how the chart itself works, what it is showing me. I'd like to know if anyone can explain more or less in dummy terms... or point me to a book/site that does it well... I've been reading a lot of explanations, but it's just hard for me to visualize it.

I apologize for this confusion! Thank you for any help!

Some comments pertaining to your questions

A few years ago on this list a lady from Australia asked about calculating houses and inverting signs and all that stuff, finding herself very confused. I calculated several charts for her. All had the same longitude but each had a different latitude, ranging from southern Australia to Japan. The sequence of charts showed her that the rising sign remained much the same (shifting for latitude distortion) and the MC sign stayed the same (moving a little bit due to my choosing land/city points to facilitate chart casting for a specific locality) .

The confusing of sign reversals etc. is only related to the math required to use a Table of Houses constructed for the nothern hemisphere to serve in calculating houses for the southern hemisphere. The Sun still rises in the east. The north finds its MC in the south, the south finds its MC in the north. BUT, all the signs and houses have a continuity in charts cast for any latitude (north and south) for the same time.

As for how to visualize a 3-D dome of sky in a 2-D chart; just visualize pulling down the sky from overhead to the horizon, collapsing the sky above into a band of stars at the horizon. All the visible stars and planets will be along the horizon. The planet positions are then slightly adjusted to be projected down/up to the ecliptic plane which is 23+ degrees tilted to the horizon. It doesn't make for too much distortion of position.

Now, this collapsing of the sky to the horizon or the ecliptic plane doesn't serve those who use declination charts but then so few actually use them. Most of us use a 2-D view of the sky. That is not necessarily wrong, its just one way of recognizing that the planets all live and work in the neighborhood of the Sun's apparent path in/through the sky. Since most of us use just planets in our charts, that is OK. Not much changes if we plunk in a few asteroids (in most cases) but it starts to get strange if we use stars, black holes and other deep space objects (of which there are very many).

Keep in mind that only the planets in a chart, plus the MC, Asc., and Vertex are "real" in terms of being actual physical bodies or as primary great circle points of orientation relative to a certain time and place on the globe. House cusps, arabian parts, appogees, etc. are all mathematical constructs. All physical objects far from the ecliptic plane may be hard to use due to the difficulty in projecting them across the horizon to the ecliptic plane such that one feels comfortable about the exactness of "contact" in the chart with the planets. This latter point is important because some such element may actually rise across the eastern horizon and hour or two earlier or later than a planet which has the same projected position on the ecliptic. This why many software programs provide a "speculum" with each chart indicating a body's ecliptic position and its rising, culminating, setting and anti-culmination times. Moon and Pluto, as well as the fixed stars are great examples of this visual phenomena.

Hope this helps. Dave

Dave's given a good account there but has used a few technical terms which you may or may not be aware of. So I'll try something a bit more primitive

Imagine you're on a ship sailing due south in the Atlantic. You are just north of the Tropic of Cancer and as you face the sharp end of the ship just before Sunrise, you might catch a glimpse of Mercury or Venus rising in the East (over your left shoulder) . At the moment they're too near the Sun to actually see them, which is called combustion by Traditional Astrologers. The Sun will rise just behind your left shoulder (just North of East) at this time of year and you would be able to watch it climb in the sky, arcing from left to right. It will reach it's highest point (culmination) right in front of you - that is due South at local Noon. It will then continue to more to your right but getting lower till it eventually sets just North of West. During the day the Sun will have moved through the area of the Sky which in the chart will be the 12th to the 10th Houses, reaching the MC at Noon and then through the 9th, through the 8th and 7th Houses reaching the Descendant at Sunset. It's then out of view but will 'continue' on its apparent journey reaching the IC at local midhight and then coming back to the Ascendant for Sunrise.

Now as Dave says local Noon will be the same whether you are north or south of the equator as long as you stay on the same line of longitude. So our ship heading south will have the same local Noon and consequently have the same MC (currently about 26 degrees Leo) at Noon.

If we could trace out the line of the Sun's motion from rising to setting (and back again) we would have drawn out the ecliptic. The point where it crosses the eastern horizon is the Ascendant. If we use the Sun's current location of 26 degrees Leo, clearly as it rises, culminates and sets so 26 Leo has moved from the Eastern horizon to the Western horizon, the ecliptic is 'revolving'.

The Ascendant does not always rise at the same geographical co-ordinate, even for the same location. It changes during the day, circulating between North of East and South of East, Starting at due East, 0 Aries will rise in the east, then Aries through to 0 Cancer it moves further North and then from Cancer through Libra it moves back to due East, reaching due East at 0 Libra. So Aries through to Virgo inclusive are the signs of Northern Ascension and from Libra through to Pisces inclusive we have signs of Southern Ascencion. In the Northern Hemisphere the Sun in the Northern signs brings days longer than nights. In the Southern Hemisphere the Sun in the signs of Southern Ascension bring days longer than nights. At 0 Aries and 0 Libra the Ascendant is due East and when the Sun is at these degrees we have the two equinoxes. Traditionally Northern Signs were called 'Commanding' and the Souther signs 'Obeying' because of the daylight differences in the North. This 'declination' North or South is something that just cannot be shown on a 2D chart the Ascendant is always shown as due East or 9 o'Clock.

Let's assume the ship continues across the Equator, at which point the Sun will culminate directly overhead and then sails on in a straight line due South till it passes the Tropic of Capricorn.

All that I've described still goes on in exactly the same way but if you are still facing the sharp end it will happen behind you. In order to see the Sun's ascent and culmination you will have to turn completely around and face North. Facing the other way means that the Sun will rise to your right and set to your left. This is not because you are in the Southern Hemisphere it is because you are facing North. Facing South in the Northern Hemisphere means you can see the Sun culminate, facing North in the Southern Hemisphere means you can see the Sun Culminate.

Now for the chart, it's not necessary for you to see the Sun, all that is nescessary is that you can chart the ecliptic. Conventionally charts are shown with East to the left, so a chart in the Northern Hemisphere shows what is going on 'in front of you. In the Southern Hemisphere it shows what is going on 'behind you' using our ship analogy.

The Sun by definition is always on the ecliptic, but the planets are merely in the Zodiac (the band of about 8 degrees around the Suns path. The planets usually appear to be above or below the ecliptic thus if you look in the night sky at two planets in conjunction you might actually see some clear 'vertical' difference between the two as well as a little lateral separation as well. So as well as declinations North or South of the equator, we have deviations above or below the ecliptic by the planets, this is referred to as Northern or Southern latitude. Again these cannot be shown on a 2D chart.

One of the costs of this 3D to 2D conversion is that sometimes a chart may show a planet just below the Ascendant but if you go outside and look you can actually see that it's risen. There's some error resulting from the process which can put a planet at a slightly different point than it really is. With odd bodies like Chiron and Pluto and other Kuiper Belt objects, their latitude is often so extreme that they aren't even in the Zodiac, so as Dave says, you have to go through complex maths to arrive at a 'zodiac' degree. However, you can happily ignore those issues LOL.

The Sun's maximum declination to the Equator is 23.5 degrees North (Tropic of Cancer) or South (Tropic of Capricorh) Because planets can also have latitude relative to the ecliptic it's possible that they may have a declinaation further North or South than the Sun's maximum. At such times they are said to be Out of Bounds (Traditional) or Exdek (Modern). Again such circumstances can't be shown on a 2D chart.

Ps

On reading both my post and Dave's I realise we've both made the assumption that you know what the Ascendant and MC are in terms of celestial geometry and Dave's made the assumption you have heard of great circles and the Vertex.

So:

[1] A great circle is a circle about the Earth which has as its centre the centre of the Earth - if you could cut through the Earth along a great circle you would divide it into two equal halves.

[2] The MC is on the intersection of two great circles. Firstly the Line of Longitude that you are standing on (all lines of longitude are great circles though they only count up to 180 degrees they double that by measuring that distance both East and West) And secondly the Eclipitic which is the Sun's apparent path around the Earth. We get these two great circles to cross, either by extending the line of longitude out in space in all directions, or shrinking the ecliptic so that it is a path along the Earth's surface. In other words we make the two fit. The opposite point the IC is also on both great circles.

[3] The Ascendant is the intersection of the ecliptic with the local horizon. Now the ecliptic is a great circle but the local horizon isn't necessarily one and indeed won't be one unless you're standing on the equator. The horizon is dependent on latitude and lines of latitude, other than the equator are not great circles. As was said in my previous post the ecliptic is at an angle of 23.5 degrees to the equator. The opposite point to the Ascendant, the Descendant is also on the ecliptic.

[4] The Vertex is something that a lot of Modern Astrologers use, though by no means the majority. It was a point put forward by Edward Johndro in the 1930's. And for the moment is best left aside till you have got the basics and even then may be something that you can happily live without.

Dave calls these points 'real' which begs a lot of philosophical questions about the nature of reality. It's perhaps best to see them as arbitrary measuring points for the moment and worry about the philosophy later. The Ascendant is the arbitrary starting point of your chart. In a quadrant House system (like Placidus or Regiomontanus) the MC is needed to calculate the angles of the chart and also the house cusps.

So the Ascendant is essential to virtually all charts cast which attempt to map the ecliptic and the MC is also essential for all the charts which divide the houses on the basis of the quadrants or angles. These two are key to transferring 3D 'reality' into 2D representation.

One final observation, we've talked about 2D and 3D representations but reality is at least 4D - Time is involved. The Sun and planets are constantly moving both along the zodiac and also in the diurnal motion of the Earth (it's revolution around it's axis). We give our time of birth for the chart and the motion is 'frozen' on that moment of time. So the chart is not just a 2D reflection of 3D space, it's a 2D reflection of 4D space. Having some software which allows you to animate the chart will give you an impresson of just how alive those movements are both during the day and over days, weeks and months.

Marina said:

...I am having a hard time relating the 2D chart to the 3D sky... and no book that I have give good explanation on what exactly is the chart showing...

Click to expand...

Years ago, when I was feeling the same frustration, I bought backyard-type astroNoMy (not astroLoGy) software called "Starry Night" and played around with the 3D sky, turned the Ecliptic on and off, moved around the globe to different locations, and just had a good time with it until I understood what the astroLoGy chart was representing.

Here is a link to the website for the product:
http://www.starrynight.com/

It looks like they have changed the product a bit since I bought it, but the "Starry Night Digital Download, Starting at: $39.95" looks about right. Simple astronomy software should help; you don't need the expensive pro editions.

That's a good idea. I invested in a cheapish telescope a few yeas ago and it came with a free Astronomy program. It allows the setting of a default location, so I can set it for my home town. I then can take a fairly clear night, cast a chart, check the Astronomy program and go out an look. I can then compare the 'real' sky with the two computer versions. It helps a lot to get a good mental picture of what's going on.

Dave, Minderwiz and Jaj, I thank you all for taking the time to answer me. *bows*

That was - well - a LOT of information, but suddenly things are becoming a bit more clear in my mind! I was going to comment on every little paragraph, but then the reply would be way too long!

Minderwiz, thank you for the imaginary 'boat trip', I absolutely loved this way of seeing things. I like when I am able to visualize how something works, helps me to understand it much more than just reading about it! I also thank you for the explanation of the 'advanced terms' you and Dave used, I'll copy all this thread an print it because of the valuable information.

Minderwiz said:

Now for the chart, it's not necessary for you to see the Sun, all that is nescessary is that you can chart the ecliptic. Conventionally charts are shown with East to the left, so a chart in the Northern Hemisphere shows what is going on 'in front of you. In the Southern Hemisphere it shows what is going on 'behind you' using our ship analogy.

Click to expand...

Wow! Okay, I feel like something just fell into place, Minderwiz! Of course, the reason why I was going nut is because the sun in my chart did not follow the direction of the sun on the sky according to the S.H. (where it moves counter-clockwise). So I was thinking what kind of inversion I wasn't doing right! But thanks to your explanation, it all makes sense. I was ignorant and did not know that the chart had this standard of keeping the east on the 9 o'clock position of the chart.

The idea of looking at the chart as if it was happening "behind me" (instead of making the chart itself mirrored) is a fantastic idea!

Minderwiz said:

One final observation, we've talked about 2D and 3D representations but reality is at least 4D - Time is involved. The Sun and planets are constantly moving both along the zodiac and also in the diurnal motion of the Earth (it's revolution around it's axis). We give our time of birth for the chart and the motion is 'frozen' on that moment of time. So the chart is not just a 2D reflection of 3D space, it's a 2D reflection of 4D space. Having some software which allows you to animate the chart will give you an impresson of just how alive those movements are both during the day and over days, weeks and months.

Click to expand...

You are absolutely right! I would like to find a software that allows me to see the chart in motion, I think it'd help me to visualize it as a 'living thing' even more. Although the chart is a snapshot, a frozen moment, the universe is constantly moving, and I think that understanding how this 4D movements appears in your chart is helpful.

~*~

Dave, your explanation about the supposed 'sign reversal' for southern hemisphere was very helpful. I was tying my brain into a knot! I found a Table of Houses made for the S.H., and I checked my ASC, it is the same one I get when using N.H. "charts calculators" (such at the one at astro.com), which probably do this inversion automatically. Thank you very much for making this clear to me!

dadsnook2000 said:

As for how to visualize a 3-D dome of sky in a 2-D chart; just visualize pulling down the sky from overhead to the horizon, collapsing the sky above into a band of stars at the horizon. All the visible stars and planets will be along the horizon. The planet positions are then slightly adjusted to be projected down/up to the ecliptic plane which is 23+ degrees tilted to the horizon. It doesn't make for too much distortion of position.

Click to expand...

This explanation was SO useful to me! I'll play with it a bit in my mind, to get use to the 'transition' of the 3D sky to the 2D chart.

By the way, I did not know one could use stars and black holes in charts. Mind-boggling!

~*~

Jaj, thank you for your suggestion, I think I once had this software, a free or trial version of it. I love astronomy, when my father and I were telescope junkies when his telescope worked (and when our neighborhood didn't have so much light at night). I have a software that allows me to 'visit' any known planet in the solar system and any known star in the 'visible' universe, such as Antares, Sirius, Regulus, Polaris, etc.



There was SO much more I wish to comment, but I think I need to digest all the information, play a bit with the visualization of the chart and then... come back with more questions (and perhaps a couple of realizations, I hope!).

I really hope I am not filling the forum with stupid things, but I can't think of a best place to ask these questions. I am, admittedly, very dumb when it comes to math and geometry, but I'm trying to overcome my limitations.

My brain was resembling a knot yesterday, now it's back into its usual brain-shape, thanks to your explanations of the chart and what parts of the visible sky it attempts to represent.

Thank you, once more!

When I first started out I was having much the same problem envisioning what all the technical terms meant in a geocentric "world-view" sense (even those that seemed obvious from a childhood study of geography and the solar system): equator, ecliptic, longitude, latitude, axial tilt, right ascension, horizon, meridian, prime vertical, vertex, long and short ascension, and all the rest. None of the drawings I encountered did a good job of conveying everything in one comprehensive picture, so I made my own. Now I wish I could still find it since I'm in need of a refresher after being astrologically moribund for over a decade.