Assertion: nebula | /r/CapableOf | expand by 1 arcsecond
Facets:
value: across the sky
type: LOCATION
Source sentences:
text: The nebula expands at a rate of at least 43,000 miles (about 69,000 km) per hour, or about 12 miles (19 km) per second), which means that it expands by 1 arcsecond across the sky every 100 years.