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
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
Mu Cephei is a red supergiant star, the reddest star visible to the naked eye. It has an estimated surface temperature of 3,551 K (3,278 °C; 5,932 °F). This temperature is hot enough to cause the star to emit a reddish-orange light, which is why it has earned the nickname Herschel’s Garnet Star. The color is caused by the absorption of blue and green light by the star’s atmosphere, which is composed mostly of hydrogen and helium.
Mu Cephei is a red supergiant star, the reddest star visible to the naked eye. It has an estimated surface temperature of 3,551 K (3,278 °C; 5,932 °F). This temperature is hot enough to cause the star to emit a reddish-orange light, which is why it has earned the nickname Herschel’s Garnet Star. The color is caused by the absorption of blue and green light by the star’s atmosphere, which is composed mostly of hydrogen and helium.
Mu Cephei is a red supergiant star, the reddest star visible to the naked eye. It has an estimated surface temperature of 3,551 K (3,278 °C; 5,932 °F). This temperature is hot enough to cause the star to emit a reddish-orange light, which is why it has earned the nickname Herschel’s Garnet Star. The color is caused by the absorption of blue and green light by the star’s atmosphere, which is composed mostly of hydrogen and helium.
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