Ask Real Astrologers: Tropical Versus Sidereal Astrology

Looking for AnswersThis week’s question comes from Amber in Indianapolis:

I was reading your blog and saw that there are two (I knew this) methods of tracking and measuring the planets. As a person who watches trends and impacts, I would like to know if we should have information from both systems. Does that affect our birth chart data and, if so, by how much?

Thank you for your insight and sharing your real-time issues. It makes the information much more user-friendly and comfortable!

Well, Amber, I’m not often accused of being user-friendly. But thanks all the same, and thank you for an excellent and timely question.

The issue of the two systems of astrology came up in my previous two forecasts, in which I discussed the proper date for the festival of Wesak, celebrated by Buddhists as the birth, death, and enlightenment of the Buddha. Wesak traditionally is celebrated at the Full Moon in Scorpio. However, depending on the system used, this can end up being two different dates. Many Eastern countries use the sidereal system, while here in the West, most of us use tropical astrology. According to the tropical system, today’s Full Moon is in Scorpio, but in sidereal astrology, it’s in Libra. The Full Moon on May 25 will be in sidereal Scorpio and tropical Sagittarius.

Simply put, the tropical system is a sign “ahead,” although not a full sign, but roughly 24 degrees (a sign is 30 degrees). This is not arbitrary but is based on the degree of the zodiac that appears on the Eastern horizon at sunrise on the spring equinox. This is confusing, I know, so let’s look at how it happened.

Although astrology has been around since the time of the Babylonians, it wasn’t until the 2nd century B.C.E. that Greek astrologers (they were also astronomers; back then, there was no difference) noticed that the constellations didn’t stay in the same place over time relative to the equinox. We now know that this is due to a phenomenon called precession, which is caused by a wobble in the earth’s rotation on its axis. You can envision it like a spinning top, except one full spin takes about 26,000 years. Around the time of the birth of Christ, the Sun rose in early Aries on the spring equinox. Now, it rises at around 6 degrees Pisces.

The ancient Greeks decided to address precession by carving up the sky into 12 equal parts, each representing a “sign,” and anchoring them to the solstices and equinoxes – what we call the four cardinal points – rather than the slow but constantly shifting positions of the constellations. This system became the basis for Western tropical astrology. For whatever reason, astrologers in India and the Eastern countries decided not to correct for precession. So rather than putting 0 degrees Aries on the equinox, they use the degree where the Sun actually rises, and that degree changes over time.

The key point to remember is that the signs in Western tropical astrology aren’t the same as the constellations, even though they’re named after them. One of the criticisms leveled at astrologers by scientists is that we don’t have the signs right. We certainly do, and it was an intentional decision. They are welcome to argue with the logic of that system – and many astrologers do, among themselves – but to say that astrologers don’t know the signs are “out of step” with the constellations is silly and flat-out wrong.

As for how it affects the natal chart, you may be a different sign in one system and the other, but not necessarily. If the degree of your Sun is above 23, then you’re likely the same sign in both. The same applies to your Moon, Ascendant, and other planets. If you’re curious, by all means check out the interpretations and see which system resonates more strongly with you. But once you make a choice, stay with it. Going back and forth isn’t likely to give you additional insight, but will only confuse you.

Adherents of sidereal astrology believe that their system is more accurate because it reflects the true position of the planets against the stars. I think that depends on how astrology works. We still don’t know, and so I can’t insist that they are wrong. Which system you choose to use is up to you, but I recommend picking one and sticking with it – especially if you are new to astrology.

I hope that answers your question, Amber … and that you still think I’m user-friendly. Incidentally, you might also like an article I wrote in January 2011 when this question was a hot topic in the news.

Aquarius, the sign of astrologyPat

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