NavList:

In the casting of natal horoscopes, presumably, a thorough calculation would look for the Sun, Moon and planets with respect to a) the Zodiacal signs and b) the relative position of the "horizon", "mid-heaven"   etc in a specific house system.   The relationship of these would give the horoscope.  I put "horizon" and "mid-heaven" in quotes because they're often referenced to the ecliptic and the intersection of the ecliptic with the horizon and then subdivided in various ways.  The modern software tracks these correctly and you can even choose which house system you want.  

Now, it seems like the Babylonians omitted Ophiuchus, because, even though it intruded on the ecliptic, the number 13 didn't fit with an easy factorization.   I suppose one can slice and dice the Zodiac to get 12.   

The standard "what's your sign?" is the Sun sign, and the article is roughly correct that the Sun sign has indeed changed, but this is nothing new.   At some point, the Sun signs got frozen (Ptolemy?) with a date and most people use these in the newspaper horoscopes.      

This is my understanding, but I'm not exactly an astrology expert.    Here are the new "Sun signs" according to one account:

--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. 23-29;

--Ophiuchus* Nov. 29-Dec. 17;

--Sagittarius: Dec. 17-Jan. 20.

*Discarded by the Babylonians because they wanted 12 signs per year.