<http://schema.org/alternativeHeadline>
"Astronomers can't be sure if the newly discovered galaxy really is made almost entirely of dark matter, or if it just contains stars that are too dim to be visible."^^<http://www.w3.org/2001/XMLSchema#string>
<http://www.mnn.com/earth-matters/space/stories/newly-discovered-galaxy-is-invisible-to-telescopes>