Sidereal Time and Solar Time

I have started teaching a Math course in Astrology and while most of my students accept at face value the steps to construct a chart without a computer, others really challenge me. My latest student really struggled with why Sidereal time had to be reconciled with Solar time in order to define the angles of the chart and the inner house cusps. I really struggled to come up with an explanation that was accessible to an audience that may not have a strong mathematical back ground. After about two weeks of driving myself insane, I think I’ve come up with something that explains the differences between Sidereal Time and Solar Time. This understanding can be the starting point to what is not a difficult process (creating the chart) but it is a time consuming process with many, many steps. Here we go:


There are three distinct movements associated with the Earth.The daily rotation of the earth on its axis, the Earth’s orbit around the Sun, and the rotation of the axis itself. These movements are measured by Sidereal and Solar time.
Solar time is relative to the Sun, while Sidereal Time is measured by calculating the the Earth’s movements relative to a distant star.

What is Sidereal Time?
Sidereal time is a way of measuring time based on the Earth’s rotation relative to a distant star, rather than the Sun. 
A Sidereal day is the time it takes for the Earth to complete one full rotation relative to the stars. (23 hr 56’ 04”).
A Sidereal year is the time it takes the Earth to complete one orbit (360°) around the Sun, again, relative to the stars.(366.256 days).

What is Solar Time
Solar time is a way of measuring time based on the Earth’s rotation relative to the Sun.
A Solar day is the time it takes to complete one rotation on its axis, relative to the Sun.
The earth must rotate slightly more than 360° to return to the same spot because the Earth is orbiting at the same time it is rotating, and is 24 hr 00” 00” in length.
A Solar year is the time it takes to complete one orbit around the Sun, 365.25 days.
This is why we have a leap year every 4 years.

Why does the Ephemeris “reset” sidereal time to 0 every September? 

The daily notations of Sidereal Time in the American Ephemeris increase by slightly less than 4 minutes each day. This is measuring how much of the orbit around the Sun the Earth completes each day (4’ = 1°), not the rotation of the Earth on its axis. (23hr56’04”)

In the American Ephemeris, Sidereal time resets to 0 when the Vernal Equinox, (the point when the Sun crosses the celestial equator) also crosses the observer’s meridian. This is a universally accepted convention, much like how our calendar year begins on Jan 1st. 

The Precession of the Equinox (the rotation of the axis itself)

In the context of the Precession of the Equinox, this September to September period is also referred to as a Sidereal Day. It is a measurement of the rotation of the Earth’s axis, caused by the rotation of the Earth. Similar to the spinning a top, the axis itself describes a slight arc. By extending this arc onto the celestial equator from the North Pole, the arc eventually completes one 360 degree rotation. This takes approximately approximately 25,600.

  • 71 years to move 1°, = 26,000 (23 56′ 04″ Sidereal days)
  • 26,000 days x 360° = 9,360,000 days (360° rotation of the axis)
  • 9,360,000/366.256 = 25,556 Sidereal years (25,600)


Brave New Worlds

There has been a lot of online chatter and interest surrounding Pluto’s move into Aquarius this year, and with just cause. Last year’s dip into Aquarius’ realm revealed the power of AI and it felt like giving a loaded gun to a toddler in terms of artistic creation. Gone was the clumsy tool that adapted Hallmark movies into hilariously awful scripts that had induced many an online meme in the previous three years. Suddenly writers and authors were looking at an accomplished tool that rivalled their own works, seamlessly and effortlessly. 

Pluto entered Aquarius again this January, practically holding hands with Sun, shining powerful light into the equally powerful dark. We are cautious about what this heralds for the next 20 years and rightly so. Pluto will eventually find its feet, and we will emerge stronger and more able to use the Aquarian tools we develop.

What I haven’t heard much about is the fact that we have most likely completely left the Piscean Age, and are now looking at 2500 years of Aquarian dynamics that will affect civilization. New societal norms will emerge  to shift humanity’s focus outward to new horizons, possibly quite literally, brave new worlds.

In order to realize what this shift can mean, let’s first look at the mechanics of the ages through an astronomical lens:

The celestial equator is a projected imaginary circle on the same plane as the equator of the Earth. This plane is the basis of the equatorial coordinate system. Simply put, the celestial axis equator is a projection of the terrestrial equator into space. The zodiacal belt containing the known constellations lies above us, along the path of the celestial equator.

The Earth is tilted on its axis and because of minor irregularities, the Earth wobbles as it rotates on its axis. This wobble causes the axis to describe an arc around the North and South poles. 

The arc this wobble creates around the poles completes 1 degree of a 360 degree circle every 71 years. It takes 25,800 years to complete the circle, and marks a backwards path through the zodiacal belt. This rotation was noticed because the Sun appears slightly earlier every year when compared to a fixed star. This phenomenon is referred to as the Precession of the Equinoxes.

The Egyptians were aware of this precession, but it was not documented and explained until 190 BC.

Astrologically, the Precession of the Equinoxes moves backwards through the signs, each creating an age that lasts 2500 years, more or less. There is no definitive moment for the change of sign; it occurs slowly over time drifting from one sign into the other, creating the ages. Each age is often marked by a specific event that precipitates a global shift in thinking. For example, the Age of Pisces is marked by the rise of religions including Christianity which uses the Piscean fish to describe the Fishers of Men. The sacrificial nature of the new messiah as the Lamb of God is a nod to the waning Age of Aries, symbolized by the Ram.

The Ages

Precession of AgesYearsHuman Development
Age of Leo10,000 to 8,000 BCENeolithic/Egyptian – Self-consciousness, the idea of a higher being, personified by the Sun
Age of Cancer8,000 to 6,000 BCENeolithic/Mesopotamian/Egyptian – development of city states, leading to skirmishes, a defensive military style
Age of Gemini6,000 to 4,000 BCEMesopotamian/Egyptian – trade and commerce, reliance on written language, the beginnings of diplomacy
Age of Taurus4,000 to 2,000 BCEEgyptian/Greek – developing agricultural lands, building with a sense of permanence.
Age of Aries2000 BCE to 0 CEGreek/Roman – expanding territories, creating empires with military prowess, highly structured society
Age of Pisces0 to 2000 CERoman/European/Asian – surges of religious fervour, overthrowing the strict societal rules, settling into the politics of religion
Age of Aquarius2,000 to 4,000 CEWhat will it bring? To Be Determined…

Each age begins with a period of turmoil, and then settles into its purpose. We are in the throes of those changes right now, and our transformation is one of inner consciousness, perhaps a realization of how connected we really are. These are far from new ideas, but perhaps the seeds have finally found fertile ground. 

Although Aquarius is an Air sign it is associated with Water as well. As the Water Bearer, Aquarius holds spiritual knowledge for us until we are ready to transcend into a higher consciousness, with an understanding that we cannot operate individually anymore. Our actions (or lack thereof) affect the planet and all living things; we are an integral link in the chain of life.

Our scientific minds have long understood the natural world and we are able to predict celestial events with mathematical accuracy. And now we are also aware of the harmonics of nature, the subtle effects of unseen particles that  affect and connect us in ways we have not even begun to understand.

The development of Quantum Mechanics requires that scientists must make their own leap of faith, in much the same way people of religious faith do, believing in something other than what we can see.

So what do the next 2500 years years hold for humanity? Will water become the new currency, holding more value than gold? Will we finally let go of our closely held borders as we realize we’re all in this together? Will AI be the tool we hope for and not the enemy we fear? Our Brave New World awaits…

Aspects and Orbs, Oh My!

Astrology has a language all its own, and depending on your genre of Astrology, each component, whether it be a planet, a house, or a sign, has pretty specific keywords associated with it. Even the aspects themselves are divided into easy or hard and have ease of flow or varying degrees of tension.

So as an astrologer the first stage of your development requires you to learn that language, and it can take time. The meanings of each component have to make their way from one part of your brain to the next so they become muscle memory. Much like multiplication tables in elementary school, they become intuitive, knee-jerk responses. Hopefully the transition is more enjoyable than rattling off multiplication tables.

Once the meanings are fixed, it becomes so much easier to navigate the complex art of blending two or more together in a meaningful way. It’s one thing to understand how Venus in Virgo in the 9th house (travel planner), is very different from Venus in Aries in the 10th (controlling boss, (but she’s so nice!)). The next hurdle is to place that Venus in Virgo in the 9th house in aspect to, let’s say Saturn in Pisces in the 8th.

Let’s say ol’ Saturn in Pisces, is struggling trying to figure out what’s not working. Saturn is uncomfortable in the mutable Water sign, not quite ready to go with the flow that Pisces demands. The 8th is not just taxes and super responsibility though, it is a house of deep intimacy, the dissolution of ego and the becoming one with another is also a very big part of the 8th house. These themes tie in well with Pisces, dissolution of boundaries. Saturn has great survival skills and convinced of the journey will follow through.

Now what is the aspect? Well with one in the 8th and the other in the 9th we’ll go with the obvious, the sextile. A sextile is two planets 60° apart, but once you take in a possible orb of 7° or even 10°, there’s some wiggle room, and a sextile in two adjoining houses is not rare. The sextile brings understanding and awareness of the needs of each planets.

The 8th house themes of deep intimacy and transformation do combine well with the 9th house embracer of all things new, and a willingness to change. Virgo and Pisces find common ground, both mutable and fluid in their own ways also embracing newness. Venus finds joy and Saturn brings the determination to stay the course, to not give up.

Rectification

Rectification is a time consuming process, and it will stretch every astrological muscle you possess. It is a great way to test your technical abilities and merge them with the untangible intuitive sense that astrologers must also possess.

Many professional astrologers don’t do rectifications, mostly because of the amount of time it takes combined with nebulous results. 12 astrologers are guaranteed to give 12 diifferent results. The proof, they say, is in the pudding and the rectification process must include a verification process, in order to validate the chart you have chosen. 

By using solar returns, and continuous testing of the rectified chart, its validity can be ascertained, but this also takes time. The general theory is that if the rectified chart matches past events in the client’s life, the chart can be used to match current and future events.

An unexpected benefit of working with a client on their rectification is the effect it has on the client. As you move through the events and the charts surrounding those events, the client relives the experiences, bringing up forgotten emotions, and reviewing their life through a lens of maturity that was not available to them at the time.

It is a cathartic process for the client, and well worth the hours of effort to find “the one”.