<http://schema.org/primaryImageOfPage>
"http://media.mnn.com/assets/images/2011/12/7_10.jpg"^^<http://www.w3.org/2001/XMLSchema#string>
<http://www.mnn.com/earth-matters/space/photos/comets-101-a-primer-on-the-dirty-snowballs-of-space/the-comet-lulin>