Assertion: asteroid belt's asteroid | /r/HasProperty | assigned number
Facets:
value: prior to the mid-20th century
type: TEMPORAL
value: sometimes
type: TEMPORAL
value: because of their widespread occurrence
type: CAUSE
Source sentences:
text: Because of their widespread occurrence, asteroids are assigned numbers as well as names.
text: Prior to the mid-20th century, asteroids were sometimes assigned numbers before accurate orbital elements had been determined, so some numbered asteroids could not later be located.
text: Many newly discovered asteroids still become “lost” because of an insufficiently long span of observations, but no new asteroids are assigned numbers until their orbits are reliably known.
text: Asteroids are assigned both names and numbers as there are so many.