Let’s say you live in Split, Croatia (bordering the Adriatic sea, on the other side from Italy). Someone comes and asks:
“Do you live in Europe?”
“Do you live in Croatia?”
“But I thought you said you lived in Europe?”
I do, but Croatia is a country and Europe is a continent.
“Oh, were you born in Split?”
“Oh, so you were born in Croatia?”
No – at the time Croatia was Yugoslavia.
You live in one place – one location – there aren’t three or four duplicates of you: one living in the city of Split, another born in Yugoslavia, a third living in Croatia, and a fourth living in Europe. There’s just one you – and depending on what context you define the address, you can give a location for where that one you lives. If you want to talk about political space, you say you live in Split, Croatia, which was once Yugoslavia. If you want to talk about geographic space, you say you live in Europe.
That’s exactly what sidereal and tropical are – they are two different contexts of coordinates for addressing any given point along the ecliptic of space. The context for sidereal coordinates is anchored to the stars. The context for tropical coordinates is anchored to the Sun-Earth relationship.
The misconception amongst quite a few astrologers east and west is that you must select either sidereal or tropical to address a point. That’s like saying you can only give your political location when someone asks where you live, and your geographical location is meaningless (or visa versa). Actually both your political and geographical location are meaningful, and they are not mutually contradictory. Similarly any planet at any given point on the ecliptic should be addressed and understood via both the sidereal and tropical coordinate system.
The thing that trips many astrologers and astrology-lovers up is that the way of dividing up the sidereal coordinates is not the same as the way of dividing up the tropical coordinates. Just like the political map has different borders than the geographical map, similarly the sidereal map of the ecliptic has different borders than the tropical map.
The sidereal map is a map of stellar space – aka stars. You see stars at night – and the night belongs to the moon. Thus the sidereal map is divided by the movement of the moon – averaged into 27 divisions as a result of the Moon passing through 27 segments of space, one-per-day, in the course of completing one full lap of the ecliptic.
The tropical map is a map of solar/terrestrial space – aka the sky. You see the sky during the day – and the day belongs to the sun. Thus the solar map is divided by the movement of the sun – averaged into 12 divisions as a result of the Sun passing thorugh 12 segments in the course of completing a full lap of the ecliptic (one segment per each lunar cycle).
The 27 segments of the sidereal map are anchored to a particular star, usually Citrā (“Spica”). The 12 segments of the tropical map are anchored to the Sun’s most notable intersections with the Earth’s latitudes: the two solstices and two equinoxes. Since they have different anchor points, there is no permanent correlation between the coordinates on the two maps. This is similar to how political and geographical maps do not always have the same correlation. England once extended into America and Australia, for example. Yugoslavia is no longer on the map of Europe, etc. At one point in history the first segment of the sidereal map can correlate to the first segment of the tropical map, but that correlation drifts so that at thousands of years later the first segment of the sidereal map can be 180 degrees opposite the first segment of the tropical map.
So, the correlation of the sidereal and tropical coordinates for any given location in space are history-specific. They change over the centuries.
OK, so lets say you where born when the moon was in the fourth division of the sidereal map – the “nakṣatra” called “Rohiṇī.” Where does that put your Moon on the tropical map??? Well it depends on when in history you were born. Just like if you were born in Europe – well, where does that put your birth location on the political map? It depends on when in history you were born in Europe. If you were born at a certain spot in Europe in 1975, you were born in the political coordinates of Yugoslavia. But if you were born at the same spot, but a different time in history, say 1997, you were born in the political coordinates of Croatia. Or, at the same spot but at 2000 B,C, your political coordinates would be mapped to some forgotten kingdom. In all three cases you are born in the same location – and you have the same geographical description of your location – but depending on when you were born that geographical coordinate will correspond to a different political coordinate.
So if you were born 2000 years ago when the Moon was in the sidereal region of Rohiṇī – the tropical way of addressing that spot would be some degree within Taurus, the 2nd tropical region. But if you were born today when the Moon was in the sidereal region of Rohiṇī, the tropical correspondant for that same location is somewhere in Gemini, the 3rd tropical region.
So, yes, every planet or point on the ecliptic has both a sidereal and tropical reference point. But the sidereal map has 27 divisions, and the tropical has 12. And, the correlation between the 12 and the 27 changes gradually over the course of history.
I hope this is somewhat clear.