Keep in mind that our birth charts begin in 100% astronomy... In other words, by charting the literal actual celestial locations of planetary bodies at the time of our birth, and in reference to where we are located on planet Earth. All of Astrology is based upon this: the passage of time, the seasons, the revolutions of planets and their gravity (and perhaps most simply for artists, the sky we see above and beyond us, whenever we look up).
Even astronomers are often only making hypotheses about what we don't have the technology to prove... or even see. Astrology is similar, and based upon a truly massive amount of comparative data spanning thousands of years and including ancient mythology, agriculture, and architecture, which was often based in astrology, or vice versa. You are right to think astrology combines science with philosophy, religion, art, etc. But would that not make it a social science? Likewise, would you consider psychology to be *not* a branch of science? Although we might be able to "prove" esoteric subjects like emotions or motivations someday, we're not there yet. Funny enough, that did nothing to prevent a massive pharmaceutical industry from taking advantage of our psychoses, in whatever pseudoscientific way they please as long as they present vaguely convincing evidence and gloss over side effects...often to dead silence from the "science" community, who can't be quiet for five seconds if anything woo-woo is mentioned?
I mean, it is literally difficult to market a safe, nutritious herbal product with 1000 years of tradition and documentation as "healing" or "helping" any specific condition, due to the stigma around this... Meanwhile the pharmaceutical industry often markets embarrassingly ineffective products with few consequences. Why? I can only guess... it's because they're involved in setting the "standards"? Still feel like the "science" stigma is scientific? The first "example sentence" given in the wiki link is a discussion on whether social studies is best considered a science or an art, so as you can see this debate has gone on since time immemorial.
Only really in modern times has Science reached the dogmatic proportions where industries spend advertising dollars to "prove" what's really true, with a scalpel and stitches, creating a huge rift between institutional or academic sciences and the many sciences which have influenced civilization since before Capitalism came and conquered, with all of its monopolies on truth (which mysteriously always end up being quite profitable to the gate keepers?). These were traditional wisdoms which were proven effective, long before the advent of what your teachers preach... For example, most traditional herbal medicine is still used today for the same purposes it was back then, with scientific studies now validating the scientific chemistry of what we used to call "old wives tales" (to further remind us that men were incapable of listening to the intuition of women, and modern science was founded upon exclusivity?)
Funny how herbalists don't need a chemistry kit to identify what plants are poison and which are medicine...do you suppose we were just evolving by nibbling on poison & dropping dead 'til we figured it all out? Or tasting every plant in the forest to kick a sinus infection? That's not quite what happened, people spoke a language which has been forgotten... after colonialist Science wiped out, annihilated, and replaced it with its own. Ironically at least 40% of our medicines still come directly from plants...including many of the most effective ones, and essentially all of our food is from plants or animals. So in a manner of speaking replacing nature-based religions with "Science" is not even entirely evolutionary sound... Nature is the closest thing to god that our modern world has, and science is based entirely upon it...yet our technological advances threaten to completely destroy the planet, despite the fact that the Industrial Revolution only began a millisecond ago in terms of the life span of our planet?
Alas. But if we narrow the definition of each word I just used I wouldn't be able to speak anymore, and I'm sure some people would prefer that. I think the disconnect is not in how we see astrology, but how scientists tend to view their own branch of "science" as something above a fact-based religion...meanwhile the average Christian has just as much confirmation bias to their faith. The thing about a confirmation bias, is that it's going to find a way to be something you are not aware of. I do understand the OP in thinking that to call a birth chart the "science of the soul" is a stretch, but I think that "reach" gets made any time science applies its "objective" lense to anything. Observable phenomenon is in and of its self misleading, as proven by science. We do not know enough about the universe to have 100% objective science: don't mistake the goal with the reality.
I'm not going to give sources for my claims, in part because I hold these truths to be self-evident, but mostly because all of this information is both easy and vast to research... And I am expecting anybody who is a scientist, when presented with a bunch of information they were not previously aware of, to do everything in their power to become as educated as possible. Don't sweat it, it's not your fault the textbooks that come with a six figure education omit this stuff ;)
(For real tho, I am very thankful to science, but don't exclude artists and healers, because we hold it down like we were doing long before modern science, and will do long after.)
k, one source just to get the ball rolling... http://cmajopen.ca/content/5/3/E724.short
My concern is that society is inherently already giving a certain clout value to "science," and things become omitted from our values depending upon whether or not they meet this definition. For example, in America 250 years ago we agreed by law that "all men are created equal." The book Animal Farm cleverly twisted this to, "But some are more equal than others," to demonstrate the reality of how we approach value in modern society.