According to NASA,there are actually 13 zodiac signs – not 12 as stated by the Babylonians,who divided the night sky into 12 sections to coincide with the 12 months in the year,and came up with the constellations to create star signs.

But even according to the Babylonians’ ancient stories,there were 13 constellations in the zodiac–other cultures and traditions have recognized as many as 24. They chose to leave out Ophiuchus

The constellations are different sizes and shapes, so the Sun spends different lengths of time lined up with each one. The line from Earth through the Sun points to Virgo for 45 days, but it points to Scorpius for only 7 days. To make a tidy match with their 12-month calendar, the Babylonians ignored the fact that the Sun actually moves through 13 constellations, not 12. Then they assigned each of those 12 constellations equal amounts of time. Besides the 12 familiar constellations of the zodiac, the Sun is also aligned with Ophiuchus for about 18 days each year.

The 12 star signs explained by the Babylonians include:

  • Capricorn: December 22 – January 20
  • Aquarius: January 21 – February 18
  • Pisces: February 19 – March 20
  • Aries: March 21 – April 20
  • Taurus: April 21 – May 21
  • Gemini: May 22 – June 21
  • Cancer:  June 22 – July 22
  • Leo: July 23 – August 23
  • Virgo: August 24 – September 22
  • Libra: September 23 – October 23
  • Scorpio: October 24 – November 22
  • Sagittarius: November 23 – December 21

The 13 star signs as explained by NASA – including Ophiuchus:

  • Capricorn: January 20th to February 16th
  • Aquarius: February 16th to March 11th
  • Pisces: March 11th to April 18th
  • Aries: April 18th to May 13th
  • Taurus: May 13th to June 21st
  • Gemini: June 21st to July 20th
  • Cancer: July 20th to August 10th
  • Leo: August 10th to September 16th
  • Virgo: September 16th to October 30th
  • Libra: October 30th to November 23rd
  • Scorpio: November 23rd to November 29th
  • Ophiuchus: November 29th to December 17th
  • Sagittarius: December 17th to January 20th