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

Early telescopes made their round glowing shells look like faint discs of planets. The figure is taken from NASA Science, 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.

Mondo Knows Facts

Planetary nebulae have nothing to do with planets

Early telescopes made their round glowing shells look like faint discs of planets William Herschel coined the name because the objects resembled small planetary discs in his telescope. They are actually shells of gas thrown off by dying Sun-like stars, lit up by the exposed core left behind. A planetary nebula glows for only some tens of thousands of years before fading. It sits in Mondo's space collection, one of 200 facts that each trace back to the reference below.

Where this comes from

NASA Science

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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Tags: nebulae, stellar, naming

Planetary nebulae have nothing to do with planets: the short answers

Where does this come from, and can I check it?: Early telescopes made their round glowing shells look like faint discs of planets. The figure is taken from NASA Science, 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.