The Hubble Space Telescope is shown following its release from the space shuttle Discovery Wednesday, February 19, 1997. The Hubble Space Telescope, one of NASA'S crowning glories, marks its 25th anniversary on Friday, April 24, 2015. With more than 1 million observations, including those of the farthest and oldest galaxies ever beholden by humanity, no man-made satellite has touched as many minds or hearts as Hubble. (Photo by AP Photo/NASA)

An employee of the National Park Service takes a selfie with President Barack Obama, left, in the background meeting with the crowd after a tour of Everglades National Park on Earth Day, Wednesday, April 22, 2015, in Florida. Obama used the visit to warn of the damage that climate change is already inflicting on the nation's environmental treasures. (Photo by Lynne Sladky/AP Photo)

Hair artist and barber Nariko, 27, etches an image of Barcelona's Neymar on the head of customer Luiz Fernadez, 15, before the Champions League semifinal first leg soccer match between Barcelona and Bayern Munich, at his barbershop in Sao Vicente, near Santos, in Sao Paulo state May 6, 2015. Nariko, who was motivated to get into the profession by his grandfather and uncle, has been etching profiles of the famous onto the sides and backs of heads for about a year or so. (Photo by Nacho Doce/Reuters)

Chechen Interior Minister Ruslan Alkhanov greets participants of the military parade to mark the Victory Day in Grozny, Russia, May 9, 2015. Russia marks the 70th anniversary of the end of World War Two in Europe on Saturday with a military parade, showcasing new military hardware at a time when relations with the West have hit lows not seen since the Cold War. (Photo by Reuters/Host Photo Agency/RIA Novosti)

In this April 23, 2015 photo, friends Jia Haixia, left, and Jia Wenqi work to plant a tree in a field in Yeli village near Shijiazhuang city in northern China's Hebei province. For the past 13 years, Jia Wenqi, who has no arms, and Jia Haixia, who is blind, have worked together to plant and water more than 12,000 trees near their village. (Photo by Helene Franchineau/AP Photo)

An aerial view of the holy Muslim Shiite shrine of Imam Moussa al-Kazim as pilgrims gather to commemorate his death, in the Shiite district of Kazimiyah, Baghdad, Iraq, Wednesday, May 13, 2015. The anniversary of 8th century Shiite Imam Moussa al- Kazim drew tens of thousands of Shiites from all walks to converge on his golden-domed shrine in northern Baghdad. The pilgrims typically march to the shrine while hundreds of tents are erected to offer them free food, drinks and services. (Photo by Hadi Mizban/AP Photo)

Activists protest the Shell Oil Company's drilling rig Polar Pioneer which is parked at Terminal 5 at the Port of Seattle, Washington May 16, 2015. Hundreds of activists in kayaks and small boats fanned out on a Seattle bay on Saturday to protest plans by Royal Dutch Shell to resume oil exploration in the Arctic and keep two of its drilling rigs stored in the city's port. (Photo by Jason Redmond/Reuters)

A reveller sleeps on the pavement during the Sanja Matsuri festival in the Asakusa district of Tokyo May 17, 2015. The Sanja Matsuri festival attracts over about one million visitors over its duration of three days, when parties of revellers carry portable shrines through the Asakusa neighbourhood, rocking and shaking them in a belief that this intensified the powers of the deities that reside inside them. (Photo by Thomas Peter/Reuters)