Assertion: universe | /r/HasProperty | proved in 20th century
Facets:
value: along the expansion of the universe
type: TEMPORAL
Source sentences:
text: The existence of the Earth's galaxy, the Milky Way, as its own group of stars was only proved in the 20th century, along with the existence of "external" galaxies.
text: The existence of our galaxy, the Milky Way, as a separate group of stars was only proven in the 20th century, along with the existence of "external" galaxies, and soon after, the expansion of the universe seen in the recession of most galaxies from us.