NASA scientists do not study astrology; nor are they responsible for the creation of a little-known 13th zodiac sign.

They do blog on Tumblr to set the record straight, though. Repeatedly.

On NASA's official Tumblr page, the space agency shut down rumors that it had drastically shifted the astrological calendar so that star signs were thrown off. Social media users have widely shared graphics claiming that NASA was responsible for adding Ophiuchus, a new 13th zodiac, to the traditional 12-sign lineup.

The hoax has resurfaced a number of times in the last decade. NASA's blog post was originally written in 2016 when rumors about a zodiac shakeup made the rounds then, but the agency reshared it this week to loop the rest of the internet in.

NASA didn't "create" this zodiac sign. Ophiuchus is one of the 13 major constellations in the zodiac, according to ancient Babylonians. The Babylonians left it out of the zodiac because they followed the 12-month calendar and assigned the other 12 constellations, or zodiac signs, to different months. Ophiuchus didn't make the cut, NASA wrote on Tumblr.

Another more obvious point the agency had to make in its post: NASA doesn't study astrology. That's a pseudoscience, which means its tenets are not rooted in fact, not that that's stopped thousands of years of Earth dwellers from turning to the stars to dictate their future.

But the Western zodiac is based on very real constellations, the shapes of which inspired the ancient Greeks to develop mythology around them. Early astrologists assigned meanings to each of the 12 zodiac symbols that were thought to inform the temperament of people born within each sign's duration. There's no scientific basis to what each zodiac means, though.

NASA scientists are astronomers who study space and astral bodies, including stars. The agency does not preside over the astrological calendar, but it has observed how the positions of constellations have shifted since the Babylonians divvied up the zodiac 3,000 years ago.

Here's NASA's explanation:

"The constellations are different sizes and shapes, so the sun spends different lengths of time 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."

So don't blame NASA if you suddenly doubt your lifelong star sign. Blame the Babylonians for neglecting Ophiuchus in the first place.

text by Scottie Andrew, CNN