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I want to know the answer to the question in the title, I want to see how much heat energy can a body emit during present in lonely space without any contact of other body.

By knowing this I can understand how much heat the helium atoms losing in the "sun" of our galaxy.

uhoh
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Amit Ranjan Sahoo
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  • for the sun, https://en.wikipedia.org/wiki/Sunlight#Composition_and_power , look at the appproximate fit of black body radiation – anna v Nov 07 '22 at 12:38

2 Answers2

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If the object is in thermodynamic equilibrium (internally, not with the surroundings), i.e., when it can be characterized by temperature, then the heat emission rate is described by Stephan-Boltzmann law.

Perhaps relevant: Stefan–Boltzmann law applied to the human body.

Roger V.
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  • What I don't see clearly covered in that article is that emissivity is generally wavelength dependent. – uhoh Nov 07 '22 at 23:30
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What is rate of emission of heat from a body at space ?

It all depends on whether the body has a source of internal heat, and how far it is from a source of external heat such as a star. The Sun itself obviously emits a huge amount of energy - about $4 \times 10^{26}$ watts - most of it as visible light or infrared radiation. The earth emits about $1.2 \times 10^{17}$ watts, which is almost the same as the energy it receives from the Sun (there will be a small difference due to natural sources of heat such as volcanoes, human-produced heat and global warming). The Voyager 1 spacecraft emits about 330 watts of heat due its RTG nuclear power source. A comet way out in the Oort cloud will emit almost no heat at all.

gandalf61
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