Rulership dates of Signs are different

Abrac

I'm not very knowledgeable when it comes to astrology so I apologize if this is a dumb question. Lately I've noticed in books that the dates a sign rules are frequently different. For example one might say for Taurus April 21 - May 21 and another April 21 - May 20. Are they typos or do different people just do it differently? Is there one arrangement that's supposed to be the most "right" or official? Thanks.
 

Minderwiz

It's question. The dates given arethe dates when the Sun enters the sign each year. But, and it's a big BUT, the dates and times actually vary a little from year to year.

There are several reasons for this, the most obvious one being the time difference between locations on Earth. at the time I'm writing this it's coming up to 22:00 on July 4th. For someone in central Russia it's already July 5th. So a planetary ingress now would have different dates depending on where you live. Some columns will claim local time, others will take a standardised location such as London or New York.

Even allowing for that issue there is a second cause for variation because the Sun's observed circuit of the zodiac takes slightly more than a year (which is why we have leap years). You will find a four year cycle for the times of the solar ingress into signs. These an shift the ingress back or forth into either the preceding date or the following date.

There are other small variations in the Earth's orbit of the Sun and the Earth's rotation which overlay the four year cycle.

The result is that any attempt to provide standard dates will be factually wrong in some years. So treat the dates as loose guides. If, like me, your birthday falls near to a sign change, you should check the date and time of the ingress for your birth year at the location of your birth.
 

Abrac

I get it now. Much appreciated! :)