U.S. Marines, left, and South Korean Marines, wearing blue headbands on their helmets, take positions after landing on the beach during the joint military combined amphibious exercise, called Ssangyong, part of the Key Resolve and Foal Eagle military exercises, in Pohang, South Korea, Saturday, March 12, 2016. North Korea said Saturday its military is ready to pre-emptively attack and “liberate” the South in its latest outburst against the annual joint military drills by the United States and South Korea. (Photo by Kim Jun-bum/Yonhap via AP Photo)

Bronze whaler shark (Carcharhinus brachyurus), caught in traditional seine net and released by fisherman, Muizenberg beach, Cape Town, South Africa on October 11, 2016. Action shots have captured fishermen trying to free a potentially deadly Bronze Whaler shark who was caught in their nets. The incredible images show the eight-foot-long 500-pound predator lunging its mouth towards the fishermen who are desperately trying to pull it back into the safety of the sea by its tail. Eventually they succeeded. (Photo by Chris and Monique Fallows/NPL)

A one month old Turquoise colored Green Veiled Chameleon perches on a finger in the Cardin's Chameleons boothat Repticon 2014 Sunday, August 3, 2014 in Jacksonville, Fla. The vendor specializes in captive bred and born Veiled Chameleons and this particular specimen cost $40.00. The Repticon reptile and Exotic Animal show made its stop in Jacksonville over Saturday and Sunday offering a variety of cold blooded critters and related supplies for sale at the University Center on the University of North Florida campus. The show, which travels nationally stops in Jacksonville several times a year according to event vendor team leader Patty Healey. (Photo by Bob Self/AP Photo/The Florida Times-Union)

Relatives of the crashed AirAsia plane passengers pray at Juanda Airport, in Surabaya, Indonesia, 31 December 2014. Indonesian rescuers retrieved three more bodies from the sea on 31 December but the search to recover more victims from the AirAsia plane crash was hampered by bad weather, the recue chief said. AirAsia Indonesia flight QZ8501 crashed into the Java Sea on 28 December, about halfway through a two-hour flight between Surabaya, Indonesia's second largest city, and Singapore. (Photo by Made Nagi/EPA)

French firemen wearing chemical protective suits take part in a mock chemical attack exercise at the Geoffroy Guichard stadium in Saint-Etienne, France, April 4, 2016 in preparation of security measures for the UEFA 2016 European Championship. (Photo by Robert Pratta/Reuters)

Apollo 9 Command/Service Modules (CSM) nicknamed “Gumdrop” and Lunar Module (LM), nicknamed “Spider” are shown docked together as Command Module pilot David R. Scott stands in the open hatch. Astronaut Russell L. Schweickart, Lunar Module pilot, took this photograph of Scott during his EVA as he stood on the porch outside the Lunar Module. Apollo 9 was an Earth orbital mission designed to test docking procedures between the CSM and LM as well as test fly the Lunar Module in the relative safe confines of Earth orbit. (Photo by NASA)

On August 31, 2012, a long filament of solar material that had been hovering in the sun's atmosphere, the corona, erupted out into space at 4:36 p.m. EDT. The coronal mass ejection, or CME, traveled at over 900 miles per second. The CME did not travel directly toward Earth, but did connect with Earth's magnetic environment, or magnetosphere, causing aurora to appear on the night of Monday, September 3. (Photo by NASA/GSFC/SDO via The Atlantic)

A street cleaner demonstrates his martial arts skills in front of a closed shop near Beijing's Tiananmen Square September 2, 2015 as the capital prepares for tomorrow's parade. (Photo by Damir Sagolj/Reuters)