Astro Maps in Zodiac longitude vs. In Mundo, explained

There are two ways — two schools of thought, about how to do an Astro Map, which is so essential to a relocation chart. They are:

  • Zodiac longitude
  • In Mundo

Most astrologers, myself included, use Zodiac longitude. This is meant as an explanation as to how each one works, but it’s kind of complicated.

The sun’s path in the sky, and thus on the chart wheel, takes the path of what is known as the ecliptic. Each of the planets doesn’t usually travel on the ecliptic exactly. Like, for example, the Moon.

The whole point of the Moon’s Node is that it’s where the planes of the Moon’s orbit and the Earth’s orbit around the Sun intersect. If the Moon is at either of the nodes, it is exactly on the ecliptic (and that’s where solar eclipses happen). But the Moon’s orbit is tilted 5 degrees from the earth’s orbit, which means that the Moon can be as much as 5 degrees in declination from the ecliptic of the Sun.

The other planets revolve around the Sun instead of the earth, but they’re not usually exactly on the ecliptic either — especially Pluto. If you’ve seen graphic depictions of the solar system, most of the planets appear to be on a flat plane (although, as I’m explaining, they’re not completely flat), but Pluto’s orbit — the only planet like this — is significantly tilted from that plane. Pluto can easily be 10 degrees away from the ecliptic.

A sky map, which is offered in Sirius 3.0 (developed by David Cochrane), depicts this very well.

A Sky Map

This is a little hard to figure out what it means, unless you’re properly trained, but I’ll explain a few simple things.

  • The Northern Hemisphere is what the sky looks like at that moment in time. The Southern Hemisphere is what the sky looks like “under your feet,” or underneath the earth.
  • The green, curved line is the Sun’s ecliptic.
  • The left side of each of the hemisphere circles corresponds with the Eastern Horizon. When a planet rises, it migrates right to left in the Southern Hemisphere, until it reaches the left side of the circle, where it rises on the left side of the Northern Hemisphere, and then moves left to right.
  • The right side of each of the hemisphere circles corresponds with the Western Horizon. When a planet sets, it migrates left to right in the Northern Hemisphere, until it reaches the right side of the circle, where it sets on the right side of the Northern Hemisphere, goes into the Southern Hemisphere on the right side, and then migrates right to left.
  • The point on the ecliptic (the green line) that is the left side of each hemisphere, since it’s on the Eastern horizon, is where the Ascendant is. The point on the ecliptic (the green line) that is the right side of each hemisphere is where the Descendant is.

You can see the Sun right on the ecliptic. You can see most of the planets close to the ecliptic, but not right on it. Pluto is way off the ecliptic line, and the Moon is a significant distance from the ecliptic line. The other planets are closer to the ecliptic than the Moon, but not quite on it.

The basic principle of the Zodiac longitude system is that the planets are ‘projected’ onto the ecliptic plane, even though that’s not where they actually are. There are different ways to project the planet, but one simple one is just draw a straight line from the planet to the closest point on the ecliptic. One thing that could happen is that a planet that is below the horizon, but very close to it, could be projected above the horizon. And vice versa.

David Cochrane’s research indicated that projecting planets onto the ecliptic, no matter how far they were originally, comes up with the most accurate results. It seems totally counterintuitive, but that’s what the research has shown. That may be the reason that most astrologers use the Zodiac Longitude system, although there’s another element here that I’ll explain in a minute.

(In Mundo does not project planets onto the ecliptic. In Mundo literally means, in the world, or what is actually there, at least in theory.)

Moving back to the Astro Maps: they look radically different in In Mundo vs. Zodiac Longitude. Here’s Zodiac Longitude (using Sirius 3.0):

A Zodiac Longitude Astro Map, basic (only includes conjunctions to the Ascendant, Descendant, Midheaven, or IC

This is straightforward, because it’s a basic map. We see the Jupiter Ascending line more or less parallel to the Saturn Descending line, going through the middle of the country. We also see the Mars IC line, in other words, where Mars is at its lowest point in its route around the Ecliptic, underneath the Earth. It more or less goes through Philadelphia.

We are going to get more detailed in the next map, just to explain what kind of things are used. But it’s the same map.

A detailed map in Zodiac Longitude. The same map, but includes more aspects.

Using the detailed map, across the United States there are many lines. For example, through Denver you can see a “Pluto sextile the midheaven line,” which is straight up-and-down. It’s the modern symbol for Pluto, the PL combined, with the asterisk, which indicates sextile.

We can also see the Mars trine ascendant line (the Mars symbol with the triangle), going diagnonally through Mexico, western Texas just east of El Paso, and upwards through the Great Plains until it ends up just west of Winnipeg, Canada. Pay attention to this line, for later. And take note: according to Zodiac Longitude, Mars trine the Ascendant is the same thing as Mars sextile the descendant, since 120 + 60 = 180.

The same Zodiac longitude map, zoomed in to the middle of the country.

This is the same map, zoomed in. In general, it’s best to save the detailed maps for a more zoomed in map, since there are so many lines when we focus on a large part of the continent, whether the U.S., Europe, or other large area, that it starts to appear unmanageable. In this map we notice a lot of lines going near Kansas City, including:

  • Venus trine the Midheaven
  • Uranus sextile the Midheaven
  • Mercury sextile the Ascendant
  • Moon sextile the Ascendant
  • Venus/Pluto midpoint conjunct the Ascendant
  • Saturn opposite the Ascendant (or conjunct the Descendant)

Remember where these lines are, because now we’re going to look at an In Mundo map.

A Basic In Mundo map.

This looks about the same as the In Zodiac map, because we’re only including conjunctions or oppositions to the four basic angles. But what happens when we include the more detailed sextiles, trines, squares, and so forth?

A detailed In Mundo map.

Wow. Just, wow. This looks, to say the least, completely unruly. It appears not to make sense. Why are many of the lines going in the opposite direction, to create these crossing lines? Let’s zoom in.

The same In Mundo map, close up in the middle of the country.

To give ourselves an idea, it’s important to focus on the things that we know make sense, and then go from there.

We can see that the Saturn descending line is still in the same place, and still parallel to the Jupiter ascending line. (The depiction for the Saturn descending line is in green, indicating that Saturn is conjunct the Descendant. Green indicates aspects to the Descendant. In the “normal” Zodiac longitude map it’s depicted as Saturn opposite the Ascendant, which is the same thing as conjunct the Descendant.

To cut to the chase, in In Mundo, which technically means, “where things actually are,” a planet sextile the Ascendant is not at all the same thing as a planet trine the Descendant, when you’re plotting these lines on a map. When you move a line across the earth like that, that planet has to be 120 degrees from the Descendant at all times. Or 60 degrees from the Ascendant, which is not the same thing when you move north or south.

Let’s try to find those planetary lines that were so clear in Zodiac longitude:

  • Venus trine the Midheaven
  • Uranus sextile the Midheaven
  • Mercury sextile the Ascendant
  • Moon sextile the Ascendant
  • Venus/Pluto midpoint conjunct the Ascendant
  • Saturn opposite the Ascendant (or conjunct the Descendant)

The Midheaven lines are pretty much in the same places — the Midheaven or IC lines hardly change, if they change at all.

Mercury sextile the Ascendant is simply not in the image. But Mercury quincunx the Descendant (which, in In Mundo, is not the same thing as Mercury semi-sextile the Ascendant, although those two lines WILL cross somewhere) runs northwest to southeast, crossing through Kansas, southwest Missouri, and Arkansas).

In this chart, the Moon is one degree from Mercury, so, just like Mercury, the Moon sextile the Ascendant is not in the image. Moon quincunx the Descendant runs northwest to southeast, a line that is a bit west of the Mercury quincunx the Descendant.

The Venus/Pluto midpoint conjunct the Ascendant is not there. The Saturn conjunct the Descendant IS there, however, as conjunctions and oppositions are far less problematic than sextiles, squares, trines, etc. The line isn’t exactly in the same place, but it’s close.

I looked on the detailed image of In Mundo for the whole country and you can see both Moon Mercury trine the Descendant on the left side of the image, southwest of California. Those lines will cross the lines of Moon and Mercury, respectively, sextile the Ascendant in Zodiac, somewhere south of this image. As addressed earlier, Mars sextile the Descendant, as well, also runs northwest to southeast in the Pacific states (Washington, Oregon, Nevada, and California), and will eventually cross the line where the Mars sextile the Ascendant in Zodiac goes, somewhere south of there.

Besides the fact of the chaos that’s depicted on the In Mundo map, there may well be other reasons why many astrologers prefer Zodiac longitude if there’s a choice to be made. At this point it becomes a matter of what interpretations make more sense, rather than which method is more mechanically correct.

Some of the research indicates that the Zodiac longitude maps are more accurate when it comes to how “true” the interpretations are, but debate on the subject still exists.

By David Muir

David Muir recieved his PAC as a 2020 graduate of the Avalon School in Vibrational Astrology. He has been a practicing astrologer having studied astrology since 1997. He specializes in relocation astrology, particularly in terms of how both one's character and external influences change in a new location. He has interests in compatibility, and just generally “getting the necessary information out there for you,” which can entail personology as well as different interpretations in general. David writes a 2x/weekly blog in both relocation astrology and other astrological topics of interest, on

David received a BA from Carlow University in 2011 with concentrations in philosophy, writing, and political science. He does a 2x/month radio show and has lived in Denver, CO since 2016.

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