You may have a new zodiac sign.

Yesterday was my birthday, and I’ve always considered myself a Capricorn, but an astronomer is out there today popularizing the fact that the Earth’s true North is moving in the heavens. I will try to explain this in short, but what it means is that for a good part of our lives, we have had a different zodiac sign than the one we think we have.

The blog link above gives the following dates:

Capricorn: Jan. 20 – Feb. 16
Aquarius: Feb. 16 – March 11
Pisces: March 11- April 18
Aries: April 18- May 13
Taurus: May 13- June 21
Gemini: June 21- July 20
Cancer: July 20- Aug. 10
Leo: Aug. 10- Sept. 16
Virgo: Sept. 16- Oct. 30
Libra: Oct. 30- Nov. 23
Scorpio: Nov. 23- Nov. 29
Ophiuchus: Nov. 29- Dec. 17
Sagittarius: Dec. 17- Jan. 20

Now, you might wonder, how did this all of the sudden come about? Well, like I said, it has to do with Earth’s true north. If the Earth had a pole sticking out at the North Pole, where would it point in the heavens? We all know that the North Star, Polaris, has its name because that pole seems to point almost dead-on to the spot where Polaris is. In reality, it’s off by just a bit. The Earth wobbles like a top over 22,000 or so years, so it’s just by chance that the wobbling has put true North pointing at this star of the Little Dipper. The closest Polaris will come to being in the spot will be in the year 2102, and then, also, not exactly on.

The tilt of the Earth is not changing. It still tilts 23 degrees and gives us the seasons. This has more to do with where the tilting ball is pointing.

The Earth spins, but Polaris only moves a very little, while the rest of the stars and constellations move quite a bit. (Of course, it’s Earth moving.) Throughout the year, as the Earth then revolves around the sun, it looks like the sun is the spot of one of the zodiac constellations. They are lined up in a wavy band throughout the heavens, and the reason it’s a band like that is because North points where North is.

You might think it’s hard to see the constellation with the sun shining so bright, but what star gazers have actually done throughout the centuries is to look at what constellation appears on the horizon, where the sun set, just after sunset. (Or sunrise, in the morning.) If Aries was the constellation in the west, they knew the sun was in Pisces. So the children born in that month were born in the sign of Pisces. Then all the myths and superstitions were built around that.

So many centuries ago, the Zodiac calendar was very accurate, even if the astrology was not. But as the Earth wobbled, and the pointer moved closer and closer to Polaris, the dates at which the sun was measured to be in a zodiac constellation has changed. Another way of saying this is that the Ecliptic–the path of the sun throughout the heavens–is changing. (Ecliptic relates to the word eclipse, and of course an eclipse is yet another way to see which constellation the sun is in.)

One example of the Ecliptic: currently in south central Pennsylvania, you can get a nice view of Taurus, Gemini and Cancer in the winter evening. The constellations are later spring and summer zodiac signs, so it makes sense that we would see them now at nighttime. Especially Gemini, because the Earth is on the other side where it is during summer. In winter, we face the opposite of the sun at night, so we would see in the sky what we would see in the daytime in the summer. The sun is high up for us in June and July, and so Gemini is also high up, above Orion.

Measuring the path of the sun throughout the year has created 13 constellations for many, many years now. It sounds like someone needed an interesting blog post and so they wrote about the topic as if this were some breaking news. (Maybe it gets us off the current breaking news, which has mostly been very bleak.)

One of my uncles is very good at astronomy, but it took me until about the age of 31 to figure out what exactly was going on when I would look out in the New Jersey sky. Once I could “see” that there was a certain order to the heavens as I watched them month after month, then I could understand the theories and see geometrically (in 3-D) what was going on. Actually, it then surprised me that it took hundreds of years for the medieval astronomers to figure it out. But it did take me a while.

I put no stock in astrology, but a number of people have told me I must be a Capricorn, without knowing my sign. Oops, turns out I am a Sagittarius. I guess I better learn to spell it.