What’s “my sign”?

You’ve probably heard people ask “what’s your sign?,” expecting you to answer with the name of one of the constellations of the zodiac that are shown in Figure 2.16. What’s the meaning of this?

The question “what’s your sign?” comes from what is called astrology, which was an ancient belief system holding that our individual fates were tied to the positions of the Sun, Moon, and planets among the constellations on the dates of our births. (Be careful not to confuse astrology with the science of astronomy!) Your “sign,” or “sun sign,” was supposed to be the name of the zodiac constellation in which the Sun appears to be located on your birth date. However, in most cases you’ll find that if you look up your sun sign on an astrological web site, it will not be the same as the actual zodiac constellation in which the Sun appeared to be located when you were born (or it will be in a different portion of that sign). For example, Figure 2.16 shows that the Sun clearly appears in Pisces on March 21, but astrologers will tell you that a March 21 birthdate has a sun sign of Aries.

The reason for this discrepancy is that the astrological signs were determined about 2,000 years ago, and at that time the Sun was in Aries on March 21. However, something called the “precession of Earth’s axis” (discussed in the next section) causes the Sun’s position among the constellations to gradually shift with a cycle of about 26,000 years. Because the 2,000 years since the astrological signs were set is about 1/13 of this cycle, astrological Sun signs are now off by nearly a month (which is 1/12 of a year) from the actual positions of the Sun among the constellations today.

So if someone asks you “what’s your sign?,” an appropriate response would be to ask “do you mean my actual sun sign today, or my sun sign as it would have been 2,000 years ago?” As this question should show you, the idea that your sun sign could control your destiny really doesn’t make much sense. More importantly, hundreds of scientific tests have shown that your sun sign has absolutely nothing to do with your fate, nor is there any evidence that any other aspect of astrology can tell you anything meaningful about your life. Sun signs and astrology can be fun to talk about, but you should not take them seriously.