Where does this come from, and can I check it?

Remanent magnetism in old crust shows it switched off billions of years ago. The figure is taken from NASA MAVEN, which is linked in full on this page. Every fact on Mondo Knows names its source rather than repeating an unsourced claim.

Is this really a space fact?

Yes. It sits on the Space shelf, one of 2,600 sourced facts grouped into space, animals, the human body, history, science and more. Category pages collect every fact in the same field.

What else can I read about it?

The links under the fact point to a quiz, game, puzzle or calculator on the same subject, and the shelf below shows related facts. The wording here is original, and quoted phrases are marked as quotations.

Mondo Knows Facts

Mars once had a global magnetic field

Remanent magnetism in old crust shows it switched off billions of years ago The MAVEN orbiter maps magnetic stripes frozen into the northern crust. Without a field, the solar wind stripped much of the atmosphere over time. Volcanic eruptions in that older, wetter era left the lava plains still visible today. It sits in Mondo's space collection, one of 200 facts that each trace back to the reference below.

Where this comes from

NASA MAVEN

Facts that can change over time are reviewed and updated. If something here looks wrong, Mondo would rather know than be confidently incorrect.

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Space & Astronomy trivia

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Tags: mars, magnetism, atmosphere

Mars once had a global magnetic field: the short answers

Where does this come from, and can I check it?: Remanent magnetism in old crust shows it switched off billions of years ago. The figure is taken from NASA MAVEN, which is linked in full on this page. Every fact on Mondo Knows names its source rather than repeating an unsourced claim.
Is this really a space fact?: Yes. It sits on the Space shelf, one of 2,600 sourced facts grouped into space, animals, the human body, history, science and more. Category pages collect every fact in the same field.
What else can I read about it?: The links under the fact point to a quiz, game, puzzle or calculator on the same subject, and the shelf below shows related facts. The wording here is original, and quoted phrases are marked as quotations.