Astrology at its core is true, but not everything that everyone believes about astrology has been validated. This is important because there are contradictions in astrology that can now be corrected.
Why is it true?
It's true because of the premise that the positions of planets in the extended natal charts of people have a demonstrable effect on the choices they make. This claim has been challenged via extensive peer review and has successfully withstood criticism (see History of Peer Review).
Why does it matter?
Because if astrology is true, then this means that the foundational principles of modern science are missing a very important piece of information.
And then there is the misinformation. About a decade ago, this was written by a scientist when discussing astrology skepticism:
Anyone who is interested in making the lay public understand what science offers, and what astrology does not, needs to be informed and open to discussion. They need to be able to explain that astrology fails because its hypothesis – that the positions of the planets can influence or give information about earthly events and personalities – has not been demonstrated.
Even in 2011 this was no longer true, but very few people knew and it's an argument still made by astrology skeptics.
Is it possible that you are wrong and you just believe that astrology is true?
Yes, but the evidence is more compelling than it is for many of the areas of science that are already acknowledged to be factual. Extraordinary claims require extraordinary evidence. This extraordinary evidence has been provided by this study. It has also helped us to understand why astrology was rejected in the past.
Why does astrology exist? What's it for?
It is extremely unlikely that the phenomenon of astrology would develop naturally. This is one of the main reasons why naturalists oppose it so vehemently. It is possible that an entity creating a simulation or simulated universe may include a control program for the conscious entities within it. This is the best explanation for why astrology exists. In other words, it is a prerequisite that we don't assume a natural origin for consciousness in the universe when considering that astrology is true. In this explanation, astrology becomes a means of tracking divisions of consciousness (including people) in the simulation.
The idea that astrology is a natural phenomenon is not out of the question, but so far we can only align its effects with events in consciousness not with events in nature. Some astrologers claim astrology can be used to predict weather or geological events. These claims have, so far, not stood up to testing. It is also pertinent to mention that if astrology were part of nature, then it would be much more easy to demonstrate its truth, the fact that it is very difficult to obtain evidence for astrology suggests an alternate domain.
What are the implications for science?
Simply that there is a new branch of science that needs to be funded and the findings presented by research into this new subject need to inform and correct previous assumptions.
What are the implications for astrology?
We now understand why astrology was a difficult subject to demonstrate and we should re-assess the whole subject in the light of this new knowledge - horoscopes move and change as people do. The current population of astrologers is not bound to be interested in research or novel developments unless these developments validate their personal beliefs and practices. The way that astrologers currently deal with this information is to treat it as an add-on to what they already believe. Secondary progressions are just seen as one of many means to forecast or predict. This is what happens when you try to incorporate a new set of ideas into what is essentially a belief system - the long-held astrological tradition is the lens through which all new information and insights are viewed.
As more research and funding is given to astrology a different population will emerge that looks at the problem from the point of view of the evidence rather than the tradition.
In science, it is necessary to assess the facts of a subject with no demands that it agrees with your viewpoint, instead, you need to adapt to what the science reveals. This is not a likely outcome with astrology as it currently is because too many people make a living from it. They don't need it to be a science... and of course if our evidence challenges materialistic ideas, then the majority of scientists will not accept it either. The interested parties with most to gain are future scientists and astrologers and those people mentioned below who don't currently care.
What are the implications for people who don't care about either science or astrology?
It affects your life and relationships and provides some answers and some guidelines. Most of all it will allow us to develop a science of consciousness and to create new technology that can help us understand life and relationships (particularly the timing of events). It would be easy to improve - say - the effectiveness of dating apps and services with the application of progressed synastry and there would be demand for this if the science was more widely known about. Marginalized minorities who have to pick from a smaller pool of people, for example, lesbian and gay people, currently have to meet many more people of their own orientation before they arrive at the same astrological conditions as people who are not lesbian or gay. This only matters if astrology is true and a factor in relationship compatibility, but as has been observed, this has been demonstrated. It follows we can improve everyone's choices by creating ways for them to find astrological compatible partners.