<http://schema.org/about>
"Astronomers have detected bizarre swarms of comets that may have been trapped by the powerful gravitational pull of a huge, undiscovered exoplanet."^^<http://www.w3.org/2001/XMLSchema#string>
<http://www.mnn.com/earth-matters/space/stories/swarm-of-comets-hint-at-mysterious-undiscovered-alien-planet>