Assertion: sunspot's body | /r/HasProperty | approximated by the photosphere
Facets:
value: closely
type: DEGREE
Source sentences:
text: Although they are at temperatures of roughly 3000–4500 K (2727–4227 °C), the contrast with the surrounding material at about 5780 K (5500 °C) leaves them clearly visible as dark spots, as the luminous intensity of a heated black body (closely approximated by the photosphere) is a function of temperature to the fourth power.