Assertion: comet | /r/HasProperty | possible
Facets:
Source sentences:
text: Thus a probable candidate for the impactor is a carbonaceous asteroid, but a comet is also possible because comets are assumed to consist of material similar to carbonaceous chondrites.
text: These perturbations probably sometimes deflect long-period comets into shorter orbital periods, with Halley's Comet being a possible example of this.