[ stop the slideshow ]

17-Wei Luo-0530-DG-003

17-Wei Luo-0530-DG-003.jpg Thumbnails17-Wei Luo-0530-DG-002Thumbnails17-Wei Luo-0530-DG-002Thumbnails17-Wei Luo-0530-DG-002Thumbnails17-Wei Luo-0530-DG-002Thumbnails17-Wei Luo-0530-DG-002

Northern Illinois University geography professor Wei Luo's new study concluded that Mars once had an active hydrologic cycle that shaped the planet's landscape.