Solved cryptogram
A compass works because molten iron churning deep inside the Earth generates a magnetic field.
Earth Science Facts, sourced to U.S. Geological Survey.
What it means
The outer core is liquid metal in constant motion, and moving conductive fluid generates electric currents, which in turn generate a magnetic field that sustains the motion. The field is not fixed. It wanders, weakens and strengthens, and the rock record shows that it has reversed its polarity hundreds of times, most recently a few hundred thousand years ago.
The claim comes from U.S. Geological Survey, and the page it comes from was read on 2026-08-27 to confirm it still says this.
This is not the kind of claim that goes out of date, which is why it was set as a puzzle rather than a fact with a shelf life.
Solve it yourself
This fact is a cryptogram here: 79 letters over 20 different ones, graded medium.
- SourceU.S. Geological Survey
- CollectionEarth Science Facts
- Difficultymedium
- Length79 letters, 20 of them different
Nearby in the collection
The facts either side of this one.
- U.S. National Park Servicehard, 72 letters
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- NASAmedium, 75 letters
- NASAmedium, 74 letters
About as hard as this one
Scored closest to it by the model behind our guide to solving cryptograms.
- Royal Society of Chemistrymedium, 75 letters
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- U.S. Geological Surveymedium, 74 letters
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