The 13th sign of the zodiac is the giant constellation of Ophiuchus “the serpent charmer,” but you won’t find Ophiuchus in your horoscope. Situated between Sagittarius and Scorpius, it’s not new constellation, though it is the “forgotten” thirteenth constellation of the zodiac that astrology completely ignores.

The Sun enters the southern region of Ophiuchus on November 29 each year, remaining there until about December 18.

The Sun’s actual position in the sky according to NASA:

• Capricorn: January 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–August 10 (21 days)
• Leo: August 10–September 16
• Virgo: September 16–October 30 (45 days!)
• Libra: October 30–November 23
• Scorpio: November 23–November 29 (just a week!)
• Ophiuchus: November 29–December 17 (not an astrological sign of the zodiac ... but real all the same!)
• Sagittarius: December 17–January 20

https://www.forbes.com/sites/jamiecartereurope/2020/07/17/no-nasa-has-not-found-a-new-sign-of-the-zodiac-how-a-shifting-sky-destroyed-astrology/#243945397a51