A weeping South Vietnamese mother and her three children are shown on the deck of this amphibious command ship being plucked out of Saigon by U.S. Marine helicopters in Vietnam, April 29, 1975. (Photo by AP Photo)

A meteorite burns up in the atmosphere as seen in this photo taken near of Salgotarjan, 109 kms northeast of Budapest, Hungary, late 21 April 2015. The Moon and Venus can be seen on the left. (Photo by Peter Komka/EPA)

A woman and a child make a bonfire at a makeshift camp for migrants and refugees at the Greek-Macedonian border near the village of Idomeni, Greece, April 1, 2016. (Photo by Marko Djurica/Reuters)

Men dressed as women kiss as they take part in a parade during the Popo (Mask) Carnival of Bonoua, east of Abidjan, April 9, 2016. (Photo by Luc Gnago/Reuters)

A Pakistani vendor tries to salvage materials after flood water destroyed his shop following heavy rain on the outskirts of Peshawar on April 4, 2016. (Photo by A. Majeed/AFP Photo)

Ultra-Orthodox Jewish men prepare matza, traditional unleavened bread eaten during the upcoming Jewish holiday of Passover, in the southern city of Ashdod April 17, 2016. (Photo by Amir Cohen/Reuters)

A newly born Indian white tiger cub yawns in its enclosure at Liberec Zoo, Czech Republic, April 25, 2016. (Photo by David W. Cerny/Reuters)

A woman dressed as a character from the computer game “World of Warcraft” stands in a forest near the village of Sosnova, Czech Republic, April 30, 2016. (Photo by David W. Cerny/Reuters)