The first person to determine * the surface temperature of the Sun* (and to come up with a sensible result) was a Slovene physicist (also mathematician and poet)

**Jožef Stefan**[ˈjoːʒɛf ˈʃteːfan]. His result of 5700K differs by only 80K from the modern estimate (5780K).

He calculated it using the formula *j*=σT ^{4}* known as the

*Stefan–Boltzmann law*, (which he first formulated in 1879, his student Ludwig Boltzmann later expanded its application in 1884),

*σ*being the

*Stefan–Boltzmann constant*(also known as only

*Stefan’s law*and

*Stefan’s constant*). He’s the only Slovene scientist to have a law of nature named after him (but other things have been named after him as well, including a crater on the Moon).