The 21 Signs of the Zodiac

A Cardiff University astrophysicist was recently on our local news station and was mortifyingly introduced as an astrologer. It got me thinking about astrology and then a blog reader happened to email in with a related question:

Does the sun leave an ecliptic path through any other constellations or just the zodiac constellations? – Blossom

The answer is interesting and is also a good way to begin revealing astrology for the money-grabbing scam that it really is.

The Sun passes through thirteen constellations on its path through the sky (called the ecliptic). In traditional astrology the heavens are divided into twelve even sections of a circle. In reality the Sun spends different periods of time in each constellation. The boundaries of these constellations are entirely artificial of course. They were standardised by the International Astronomical Union around 1930, as one of the group’s first official acts.

At present, the Sun resides in the following constellations (or star signs) during the following periods of the year:

Aries: April 19th – May 13th

Taurus: May 14th – June 19th

Gemini: June 20th – July 20th

Cancer: July 21st – August 9th

Leo: August 10th – September 15th

Virgo: September 16th – October 30th

Libra: October 31st – November 22nd

Scorpius: November 23rd – November 29th

Ophiuchus: November 30th – December 17th

Sagittarius: December 18th – January 18th

Capricornus: January 19th – February 15th

Aquarius: February 16th – March 11th

Pisces: March 12th – April 18th

But it is more complicated than that! Traditional astrology is all about the relative locations of the various planets within the twelve signs. Problem is, the planets do not follow the ecliptic exactly. Each planet is inclined at an angle to the Sun in the Solar System and so they draw out slightly different paths.


In addition to the 13 constellations listed above, the planets pass through 8 more. So in a sense Cetus, Corvus, Crater, Hydra, Orion, Pegasus, Scutum and Sextans are also astrological signs. This means that there are 21 astrological signs of the zodiac. You might want to ask an astrologer how they interpret a planet in one of these ‘extra’ constellations. What does it mean if Uranus is in Scutum? Sounds painful.

Astrology is an ancient tradition that sprang up in many cultures because the stars’ apparent ability to predict certain events (crops, weather, etc). In the modern era, astrology is a con. It not something that one might believe in through tentative evidence or testimony, it is simply a fiction perpetrated by those who are able to make money from it. It is based on the principles of cold reading, gullibility  and wishful thinking. It may well be that there are things out there in the universe influencing our lives on Earth. However, the geometric happenstance that one star might look to be in a particular place at some point during your life is not going to affect your mood, your luck or your love life.

You might as well try to gain insight into your existence from the way you parked your car.


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