Did NASA Really Change the Zodiac Signs? The Truth About Ophiuchus and the 13th Sign

No, NASA did not change your zodiac sign. NASA does not practice astrology, has no authority over astrological systems, and has explicitly said they didn't change anything. What actually happened is far less dramatic than the headlines suggest — but it does touch on a real astronomical fact that's worth understanding.

What NASA Actually Said

In 2016, NASA published an educational page aimed at children on their Space Place website. The page explained that the ancient Babylonians — who developed the zodiac around 3,000 years ago — knew the Sun passed through 13 constellations along the ecliptic, not 12. But since they already had a 12-month calendar, they dropped one constellation to make the math clean.

NASA also pointed out that the Earth's axis has shifted since then due to a phenomenon called precession, meaning the dates when the Sun appears in each constellation have drifted from the original Babylonian assignments.

That's it. That's the whole story. NASA even included a clarification stating: "We didn't change any zodiac signs, we just did the math."

Media outlets stripped the nuance and ran headlines like "NASA says your zodiac sign is wrong" — and the story has resurfaced every year or two since then, always generating the same wave of confusion.

What Is Ophiuchus?

Ophiuchus (pronounced oh-fee-YOO-kus) is a real constellation located between Scorpio and Sagittarius. The Sun passes through it for roughly 18 days each year, approximately November 29 through December 17.

The constellation depicts a figure holding a serpent and has been recognized by astronomers since ancient times. The Babylonians knew it was there. They simply chose to exclude it to maintain a clean 12-sign system with each sign occupying 30 degrees of the 360-degree ecliptic.

Here's the key distinction most articles miss: zodiac signs are not the same thing as constellations.

Concept	What It Is	How It's Divided
Constellations	Irregular star groupings of varying sizes	Unequal boundaries (IAU defined 88 in 1930)
Zodiac Signs	Equal 30° divisions of the ecliptic	12 signs × 30° = 360°

Constellations vary wildly in size. Virgo spans about 44 degrees of the ecliptic. Scorpio spans barely 7 degrees. The zodiac system deliberately abstracts away this irregularity by using equal 30-degree segments. Neither tropical nor mainstream sidereal astrology uses actual constellation boundaries — they both use the 12-sign, 30-degree framework.

Adding Ophiuchus would mean switching from a sign-based system to a constellation-based system — which is a fundamentally different thing, not just adding one more sign to the list.

The Real Issue NASA Highlighted: Precession

The genuinely important point buried in the NASA story isn't Ophiuchus. It's precession.

Earth's rotational axis wobbles like a spinning top over a cycle of roughly 26,000 years. This means the position of the Sun against the background stars on any given date slowly shifts over centuries. Since the zodiac was standardized, the sky has drifted approximately 24 degrees.

This is exactly the difference between tropical and sidereal astrology:

• Tropical astrology keeps the zodiac anchored to the seasons (spring equinox = 0° Aries), regardless of where the stars have drifted.
• Sidereal astrology corrects for precession and tracks where planets actually appear against the star field.

So if the NASA headlines made you wonder whether your "real" sign is different — the answer is yes, but not because of Ophiuchus. It's because of the ~24° precession gap between the tropical and sidereal zodiacs. If your tropical Sun is in the first 24 degrees of a sign, your sidereal Sun is in the previous sign.

This is a well-known difference that astrologers have discussed for centuries. It's not a NASA discovery.

Should You Care About Ophiuchus?

For the vast majority of people, no.

A small number of practitioners use what's called "true sidereal" astrology, which maps the zodiac to actual constellation boundaries rather than equal 30-degree signs. In those systems, Ophiuchus does appear as a 13th sign. But this is a niche approach, not the mainstream of either Western or Vedic astrology.

Both the tropical zodiac (used by Western astrologers) and the Lahiri sidereal zodiac (used by most Vedic astrologers) divide the ecliptic into 12 equal signs of 30 degrees each. Ophiuchus doesn't factor in because these systems were never based on irregular constellation boundaries in the first place.

Think of it this way: Constellations are like countries with irregular borders. Zodiac signs are like time zones — evenly spaced, standardized divisions imposed on top of the underlying geography. Adding Ophiuchus would be like saying time zones are wrong because they don't follow country borders.

What Actually Matters for Your Chart

If the NASA story made you question your sign, the productive thing to explore isn't Ophiuchus — it's the real difference between your tropical and sidereal placements.

The ~24 degree precession shift affects every planet in your chart, not just your Sun sign. Your Moon, Mercury, Venus, Mars, and all other placements may fall in different signs depending on which zodiac system you use.

For a full breakdown of how the two systems differ and why both exist, read Tropical vs Sidereal Astrology: What's the Difference?. To see specifically how your Sun sign shifts, check the Sidereal Sun Sign dates and meanings.

Want to see where your planets actually are against the stars? Get your free birth chart — it shows both Tropical and Sidereal positions so you can see the real shift for yourself.