Assertion: black hole's event horizon | /r/CapableOf | spin at the speed of light
Facets:
value: almost
type: DEGREE
Source sentences:
text: On February 28, 2013 astronomers reported on the use of the NuSTAR satellite to accurately measure the spin of a supermassive black hole for the first time, in NGC 1365, reporting that the event horizon was spinning at almost the speed of light.