The Sun follows the ecliptic, and the International Astronomical Union fixed the boundaries of the 88 constellations in 1930.
Thirteen of them are crossed by this path: the twelve of the zodiac, plus Ophiuchus, the Serpent Bearer, slipped between Scorpius and Sagittarius. Observing the Sun in front of it is therefore no recent invention.
The passage times are very uneven. In 2026, the Sun crosses Ophiuchus from November 30 to December 18, about nineteen days, whereas it stays only 6 days in front of Scorpius and 45 days in front of Virgo. The constellations vary widely in size, while the signs all measure 30 degrees, about one month.
Western astrology has never counted the signs according to the constellations: it defines them as equal sectors, measured from the start of spring. Within this framework, Ophiuchus has no place to take, any more than the other constellations the ecliptic grazes. The site therefore assigns it neither a birth date nor a character reading. It does, however, show the astronomical passage of the Sun through Ophiuchus, calculated for the current year, because the fact is accurate and lets you compare the two divisions.
Family
The sky and the zodiac
The diagram
The Sun in the constellations
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Constellations and signs
History, debates, and sources
A little history
Ptolemy already includes Ophiuchus, with the Serpent it holds, among the 48 constellations of his Almagest.
Greek astronomers knew it as a figure of the summer sky, which the Sun crosses in late autumn, without making it a sign. In 1930, Eugène Delporte drew the modern boundaries for the International Astronomical Union, which confirm the ecliptic’s passage through Ophiuchus. The press has regularly revived the idea of a thirteenth sign since the early 2010s.
Sources
2
Oldest
Claudius Ptolemy, 2nd century
Most recent
Eugène Delporte, 1930
What is debated
A few astrologers propose a thirteen-sign zodiac of about 27.7 degrees each, or a zodiac based on the exact boundaries of the constellations.
The great majority of schools, Western and Indian alike, keep twelve equal signs, tropical or sidereal. Astronomy, for its part, takes no position: it merely notes that the Sun crosses Ophiuchus, and leaves astrologers to decide what a sign is.
Schools do not all agree: the site sets out the positions without deciding for you, and states the setting it uses by default.
Where this concept comes from
The authors and texts that establish or discuss this concept, with the passage when it is known.
2nd centuryClaudius PtolemyAlmagest, Books VII and VIII
Ophiuchus (the Serpent Bearer) already appears among the 48 constellations of the catalog.
1930Eugène Delporte (International Astronomical Union)Délimitation scientifique des constellations, boundary tables
Fixes the official boundaries of the 88 constellations: the ecliptic crosses Ophiuchus.
The diagram’s figures are calculated by the site’s engine (Astronomy Engine) or taken from the recorded facts, never copied by hand.
The Sun in the constellations
Sagittarius32 dDec 19 – Jan 19
Capricornus28 dJan 20 – Feb 16
Aquarius24 dFeb 17 – Mar 12
Pisces37 dMar 13 – Apr 18
Aries26 dApr 19 – May 14
Taurus38 dMay 15 – Jun 21
Gemini29 dJun 22 – Jul 20
Cancer21 dJul 21 – Aug 10
Leo37 dAug 11 – Sep 16
Virgo45 dSep 17 – Oct 31
Libra23 dNov 1 – Nov 23
Scorpius6 dNov 24 – Nov 29
Ophiuchus19 dNov 30 – Dec 18
The Sun in the constellations in 2026 (boundaries of the International Astronomical Union, calculated by the site): stays from 6 to 45 days, while each sign spans 30° (about 30 days).
Frequently asked questions: Ophiuchus, the “13th sign”
Is Ophiuchus an astrological sign?
No, not in Western or Indian astrology, which count twelve signs of 30 degrees. Ophiuchus is, however, a constellation crossed by the ecliptic. A few astrologers propose a thirteenth sign, but this position has not caught on.
When does the Sun pass through Ophiuchus?
In 2026, from about November 30 to December 18, according to the boundaries of the International Astronomical Union. They shift slightly each year. This astronomical passage does not change the astrological sign of a birth, which remains Scorpio or Sagittarius depending on the zodiac.
Why does a 13th sign keep coming up?
Because the fact is true and surprising: the Sun does cross a thirteenth constellation. The news tends to circulate as a shock headline, often without saying that signs and constellations are two separate divisions. It comes back almost every year this way.