When was this understanding updated?

The evidence had largely shifted by around 2010. Schools don't flip overnight, though — plenty of classrooms kept teaching the older version for years after researchers had already moved on.

Is "Planet X (Planet 9) exists and explains gravitational pull" true?

Distant icy objects at the far edge of the solar system kept tugging slightly out of the orbits they were supposed to follow, which led some astronomers to propose a hidden ninth planet quietly pulling strings from the dark, Planet X or Planet Nine depending who you asked. It's a genuinely elegant explanation, the kind documentaries love. Other researchers modeled an alternative: a scattered belt of smaller debris objects could collectively produce that same gravitational nudge without needing one hidden world behind it.

What you were taught

Planet X (Planet 9) exists and explains gravitational pull

What we know now

While scientists observed a strange gravitational pull in a nearby solar system, the theory that it was caused by a mystery planet (Planet X or Planet 9) was challenged in 2019. Other scientists proved that a large amount of debris could just as easily explain that pull.

Updated understanding emerged around 2010

Source Comment

Science

Common questions

Was "Planet X (Planet 9) exists and explains gravitational pull" taught in school?: Yes — and not as a joke question on a quiz. This science claim showed up in textbooks, worksheets, and classroom posters through the 2000s, which is why so many people still remember it as settled fact long after the science moved on.
Is "Planet X (Planet 9) exists and explains gravitational pull" true?: No. While scientists observed a strange gravitational pull in a nearby solar system, the theory that it was caused by a mystery planet (Planet X or Planet 9) was challenged in 2019. Other scientists proved that a large amount of debris could just as easily explain that pull. If you want the primary citation, start with Planet Nine - Wikipedia.
When was this understanding updated?: The evidence had largely shifted by around 2010. Schools don't flip overnight, though — plenty of classrooms kept teaching the older version for years after researchers had already moved on.

Is "Planet X (Planet 9) exists and explains gravitational pull" true?

Common questions

Related myths

Add a comment

Comments