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

His Sidereus Nuncius showed mountains on the Moon and four moons of Jupiter. The figure is taken from Library of Congress, 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.

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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.

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Galileo published his telescope drawings in 1610

His Sidereus Nuncius showed mountains on the Moon and four moons of Jupiter Galileo built his own instruments, reaching about 20 times magnification, and published the observations in March 1610. Within weeks he had found four moons circling Jupiter, evidence that not everything orbits Earth. The book was a slim volume of fewer than 60 pages. It sits in Mondo's space collection, one of 200 facts that each trace back to the reference below.

Where this comes from

Library of Congress

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: galileo, telescopes, history

Galileo published his telescope drawings in 1610: the short answers

Where does this come from, and can I check it?: His Sidereus Nuncius showed mountains on the Moon and four moons of Jupiter. The figure is taken from Library of Congress, 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.