<http://schema.org/url>
<http://www.mnn.com/earth-matters/space/photos/comets-101-a-primer-on-the-dirty-snowballs-of-space/cool-cousins>
<http://www.mnn.com/earth-matters/space/photos/comets-101-a-primer-on-the-dirty-snowballs-of-space/the-comet-lulin>