Assertion: planet's body | /r/IsA | planet
Facets:
Source sentences:
text: There are three rules that are applied to determine whether a celestial body can be classified as a planet.
text: In the 19th century astronomers began to realize that recently discovered bodies that had been classified as planets for almost half a century (such as Ceres, Pallas, Juno, and Vesta) were very different from the traditional ones.