NASA Principal Investigator for New Horizons mission Alan Stern (L) and Co-Investigator Will Grundy (R) hold up an enlarged, out-dated U.S. postage stamp with the "NOT YET" crossed out, during the celebration of the spacecraft New Horizons flyby of Pluto, at NASA's Johns Hopkins Applied Physics Laboratory in Laurel, Maryland, July 14, 2015. The flyby, which culminated after almost ten years of flight and over three billion miles, will allow New Horizons to photograph and collect data in the coming months. REUTERS/Mike Theiler TPX IMAGES OF THE DAY