[nonrepeating]

One of my favorite facts about sunspots is, they’re still in extremely bright, they’re only dark due to contrast. An electric arc against a sunspot would look black by comparison (given typical logarithmic brightness measurement).

[gattr]

You're right, here are some numbers:

- photosphere temperature: 5870 K

- sunspot umbra temperature: 3000-4500 K

Per Stefan-Boltzmann law, this can make the photosphere up to (5870/3000)⁴ ≈ 15 times brighter.