By Roberta Rampton YOSEMITE NATIONAL PARK, Calif. (Reuters) - The moon was just rising over Half Dome, the setting sun reflected off its sheer granite face, as President Barack Obama and his family landed by helicopter in a meadow, the knee-high grass waving wildly while campers cheered. It was a picture-perfect moment designed to resonate on social media as the White House works to cement Obama's environmental legacy as the Jan. 20, 2017 end to his time in office draws nearer. Obama brought his family late on Friday to Yosemite, one of the nation's most popular national parks, on a working vacation.
