NASA announced that it has evidence that Jupiter’s moon Ganymede, the largest moon in our solar system, has a vast ocean lurking underneath its icy crust. WSJ's Monika Auger reports. Photo: USGS/Wheaton/NASA/JPL-Caltech Subscribe to the WSJ channel here: http://bit.ly/14Q81Xy Visit the WSJ channel for more video: https://www.youtube.com/wsjdigitalnetwork More from the Wall Street Journal: Visit WSJ.com: http://online.wsj.com/home-page Follow WSJ on Facebook: http://www.facebook.com/wsjlive Follow WSJ on Google+: https://plus.google.com/+wsj/posts Follow WSJ on Twitter: https://twitter.com/WSJLive Follow WSJ on Instagram: http://instagram.com/wsj Follow WSJ on Pinterest: http://www.pinterest.com/wsj/ Follow WSJ on Tumblr: http://www.tumblr.com/tagged/wall-street-journal Don’t miss a WSJ video, subscribe here: http://bit.ly/14Q81Xy More from the Wall Street Journal: Visit WSJ.com: http://www.wsj.com Visit the WSJ Video Center: https://wsj.com/video On Facebook: https://www.facebook.com/pg/wsj/videos/ On Twitter: https://twitter.com/WSJ On Snapchat: https://on.wsj.com/2ratjSM