Birth Chart Basics
The positions in a birth chart are accurate to a fraction of a degree and can be checked against NASA. The interpretation of them has never been shown to work under controlled conditions. Both...
Every position in a chart comes from an ephemeris, and modern ephemerides are derived from the same orbital models that land spacecraft. The Sun's position at your birth is known to better than an arcsecond. Nobody disputes this, including people who dispute everything else about astrology.
So when a chart says your Moon was at 14 degrees of Taurus, that is a fact about the solar system, not a claim.
This is the part worth being straight about. The best-known test, by Shawn Carlson and published in Nature in 1985, had astrologers match charts to personality profiles and found they performed at chance. Later reviews of the literature have reached similar conclusions. There is no measured effect.
That does not mean everybody who uses astrology is wasting their time, and it does not mean the people who find it useful are fools. It means the mechanism claimed has not been demonstrated, and a site that tells you otherwise is selling something.
A chart is a structured set of prompts about yourself, delivered in the second person, that you did not write. That turns out to be a genuinely effective way to think about things you have been avoiding, and it does not require the astrology to be causal for the reflection to be real.
The honest version of the pitch is: this is an interesting and very old framework for thinking about a life, with a vocabulary rich enough to describe things ordinary language fumbles. That claim is defensible. The claim that the planets are doing it is not.
Practically, the weak point is almost never the astronomy. It is the birth time. A time recorded to the nearest quarter hour, rounded by a tired nurse, or remembered by a parent decades later can move the rising sign by a whole sign and shift every house in the chart.
If a chart reading feels wrong in a way you cannot place, check the time before you blame the technique.
| Claim | Status |
|---|---|
| Planet positions at your birth | Checkable, accurate to a fraction of a degree |
| The dates of eclipses, retrogrades and ingresses | Checkable, accurate to the minute |
| Your rising sign, given an accurate time | Checkable arithmetic |
| That a chart describes your personality | Tested and not supported |
| That transits predict events | Not demonstrated |
| That a chart is useful to think with | A matter of experience, and widely reported |
Compare two sentences. The first: your Saturn return at 29 will bring a career crisis. The second: Saturn returns to its birth position at about 29 and a half, a period traditionally associated with structures being tested, and it is worth asking yourself now which of yours would not survive that.
The first is a prediction with no support. The second is a date, a tradition, and a question. Both come from the same astrology and only one of them is honest, which is roughly the whole editorial position of this site.
what a birth chart actually is, then how to find your birth time, then how to read a birth chart.
Everything on this page is general by necessity. A reading built from your own date, time and place is the version that names your placements rather than describing the categories they fall into. If you do not know your birth time, this covers how to find it.
No. The positions are astronomy and are exact; the interpretation has not held up under controlled testing, including the 1985 Carlson study in Nature.
Yes. They come from the same ephemerides used for spacecraft navigation.
An inaccurate birth time, far more often than anything else. An hour of error can change the rising sign.
RubyAstro writes about astrology for reflection and self-understanding. Nothing here is medical, legal or financial advice, and none of it is a prediction of events. Read our full disclaimer.
Finding Your Birth TimeIf you were born in the US between 1945 and 1991, there is a real chance your birth time was recorded under a daylight saving rule your chart calculator does not know about. Here is how to check.
Your Age in AstrologyYour age tells you which house your year belongs to. It takes one piece of arithmetic, it works without software, and it is the fastest way to know what a year is about.
Finding Your Birth TimeMost of your chart does not need the hour. Every planet except the Moon stays in the same sign all day, and so does every aspect between them. Here is exactly what you keep, what you lose, and what to do about the gap.
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