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SESK: Stuff Everyone Should Know · sesk.info/aero-hr-diagram-axes

A Hertzsprung-Russell (H-R) diagram sorts stars by which two things?

True brightness and surface temperature.

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  1. Distance from Earth and age
  2. Size of planets and number of moons
  3. True brightness and surface temperature ✔

Why: The H-R diagram is a chart that places each star by its real brightness, called absolute magnitude, and its surface temperature. Where a star lands on the chart shows what stage of life it is in.

Huh, didn't know that: It is named for two astronomers, one Danish and one American, who each came up with the idea in the early 1900s.

The dad joke
Why did the star ace its chart test? It knew exactly where it stood.
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References

Answer: True brightness and surface temperature. The H-R diagram is a chart that places each star by its real brightness, called absolute magnitude, and its surface temperature. Where a star lands on the chart shows what stage of life it is in.

  1. CAP Aerospace Dimensions Module 5, Space Environment (Alaska Wing copy) akwg.cap.gov/media/cms/Module_5__Space_Environment_C640727DEF762_83c5b.pdf
    The diagram plots stars according to their abso- lute magnitude and surface temperature.
    Checked 2026-10-10.

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