At 1500 C, iron glows “[dazzling white](https://en.wikipedia.org/wiki/Red_heat)”.
At roughly 2000 C, [propane](https://en.wikipedia.org/wiki/Gas_burner) burns [blue](https://en.wikipedia.org/wiki/Gas_burner#/media/File:Propane-burner.jpg).
At 3551 C, [Mu Cephei](https://en.wikipedia.org/wiki/Mu_Cephei) earned the name “Herschel’s Garnet Star”, and this is not a reference to uvarovite.
Why?
In: 37
I think this turns out to be more of a question of human vision than physics.
The emission spectrum of molten iron really is much redder than even the reddest star. The problem is that our eyes are [very bad at judging absolute color](https://en.wikipedia.org/wiki/The_dress), they constantly make assumptions about what “white” is and adjust the color from there. Daylight (5500 K color temperature) seems to be white on its own, and so do the soft white light bulbs in my house (2800 K color temperature), but if you compare them side by side, daylight looks shockingly blue and the light bulbs a deep orange.
Molten steel is typically seen in an indoor environment, so you don’t get a good chance to compare it with daylight, and it’s so bright that your eyes adjust to it and you can’t see much else.
A propane flame, though, is different. The gas is too thin to make a strong blackbody spectrum: what you see instead is emission lines from various molecular bonds (C-H, C-C) vibrating.
https://physics.stackexchange.com/questions/64512/bunsen-burners-and-the-sun
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