About Solstaria

Solstaria is a free astrology site built around one careful calculation: the sky at the minute and place you were born. Around that birth chart sit more than fifty smaller sections, from transits, returns and the Moon’s phases to the tarot, numerology and the Chinese calendar, and a set of articles about ordinary situations, gathered under everything written. There is no account to make.

Most free chart calculators are the same handful of scripts wearing different colours. They round the time zone, they invent an ascendant when you leave the birth time blank, and they hand back a page of tables nobody reads twice.

How the chart is worked out

Positions come from a well-tested astronomical library running in your own browser, so the calculation happens on your device rather than on a server. Houses are Placidus. Close to the poles, where some degrees never rise and Placidus has nothing to divide, the chart says so and uses whole sign houses instead, and the sections that come from whole-sign traditions, such as profections and the Vedic chart, use them throughout. Aspects are limited to the five major ones, with wider orbs whenever the Sun or the Moon is one of the pair.

The part that takes the most care is the time zone. What matters is not the offset your birth city uses now, but the one it used on the day you were born, including whatever summer time rule was in force that year. That is where most free calculators quietly go wrong, and it can move an ascendant by a whole sign.

The offsets come from the IANA time zone database your browser carries. Where its record for a place reaches back only to 1970, the chart says the offset may be out by an hour. A birth time in the hour the clocks went back happened twice, so the chart asks which of the two it was; a time in the hour the clocks went forward never happened, and the chart says so and uses the moment the clocks jumped to. Places are looked up in your browser, in a list of towns loaded from this site.

What happens when the birth time is unknown

About half of the people who come here do not know their birth time. In that case the houses, the ascendant and the midheaven are not shown at all. They cannot be worked out, and an approximate one would be believed. The Moon moves about half a degree an hour, so it is worked out for midday, may be up to six degrees out, and the page says so.

What stays on your device

The name, date, time and place you enter are kept in your browser’s local storage on the device you used, so the site remembers them next time. They are not sent to the server, and there is no account and no database for them to be kept in. The same goes for what the smaller sections remember, such as a tarot spread you drew. Clearing the site data for this domain in your browser removes all of it. The full detail, including the ordinary server logs the hosting provider keeps, is on the privacy page.

What this site will not do

Solstaria does not tell you what is going to happen. It does not say whether someone will come back, whether a relationship will last, or what any of it means for your health, your money or your family. A chart is a frame for thinking about yourself, not a mechanism that runs your life.

Nothing here is medical, psychological, legal or financial advice, and the tarot, numerology and the other oracles are offered as prompts for reflection with their traditional readings, not as fortune telling. The disclaimer sets this out formally.

How the site is paid for

Solstaria carries no advertising, sells no placement and runs no advertising network. Some of the articles end with a suggestion that you might want to talk to a person, linking to an advisor marketplace we have a paid partnership with. If you follow one of those links and go on to pay for something, we may be paid a commission, at no extra cost to you. Where a page suggests speaking to a professional advisor, that link is a paid partnership and is marked as one on the page it appears on: it comes after the free part of the page, carries a plain note beside it, and is marked as sponsored in the page source. We count which link was used and when, never who used it. The details are on the affiliate disclosure page.

How accurate it is

The positions are checked against established reference software, and the sections that are plain arithmetic, such as numbers and the tarot birth cards, write out every step so a result can be checked on paper. The weak point is almost always the birth data. The ascendant moves a degree every four minutes or so on average, so a time rounded by half an hour on a certificate can shift it by several degrees, and nothing on our side can detect that.

What this is built on

Planetary positions come from astronomy-engine by Don Cross, used under the MIT licence. Place names and coordinates come from GeoNames, used under the Creative Commons Attribution 4.0 licence. Historical time zone offsets come from the IANA time zone database, which your own browser carries. Headings are set in Instrument Serif, under the SIL Open Font Licence.

Both data files are stored on this server rather than fetched from anyone else while you use the site.