Contestants of a tourism beauty pageant balance eggs on their collarbones as they cruise along the Yellow River in Jiyuan, Henan province, China, June 22, 2015. The contestants believe that if they are slim enough, their collarbones will allow them to balance the eggs securely on their bodies. (Photo by Reuters/Stringer)

Police officers detain an opposition protester during a May Day rally in Saint Petersburg, Russia on May 1, 2019. Labor Day or May Day is observed all over the world on the first day of the month of May to celebrate the economic and social achievements of workers and fight for laborers rights. (Photo by Igor Russak/Reuters)

An F/A-18 Hornet assigned to Strike Fighter Squadron One Five One (VFA-151) emerges from a cloud created when it broke the sound barrier in the skies over the Pacific Ocean, July 7, 1999. (Photo by John Gay/US Navy)

“The Qassam rocket is a simple steel artillery rocket developed and deployed by the Izz ad-Din al-Qassam Brigades, the military arm of Hamas. Three models have been produced and used between 2001 and 2011”. – Wikipedia

Photo: A rocket, similar to the Al-Qassam rockets used against Israeli is prepared for launch as new members of the Islamic Jihad fighters show their skills as they attend a military show in the former Israeli jewish settlement of Atsmona September 26, 2008 in Rafah, southern of Gaza Strip. (Photo by Abid Katib/Getty Images)

Surfer Gary Clisby rides his foil board on a morning swell of the coast of Carlsbad, California on May 23, 2018. Harnessing the “foiling” technology more typically seen on racing catamarans in sailing's America's Cup, the surfboards appear to fly above the water thanks to a fin attached to the bottom of the board. (Photo by Mike Blake/Reuters)

“Strike Through The Mothership”. Every May for the last 3 years I have driven down to Tornado Alley to capture some amazing storms. This supercell held so much promise to drop a tornado but one small shift in the atmosphere and all that it produced was an extreme lightning show. Photo location: Broken Bow, Nebraska. (Photo and caption by Vanessa Neufeld/National Geographic Photo Contest)

The Spanish photographer Xavi Bou digitally combines sequential pictures of birds to create a single image, or chronophotograph, that reveals the shapes of their flight paths against Catalonian skies. His work shows the variety and beauty to be found in the daily activities of the local birds, including spiralling storks, swooping starlings and giddy swifts. Here: European herring gulls at Llobregat Delta. (Photo by Xavi Bou/Rex Features/Shutterstock)

Long row of shiny new Flying Fortresses, part of huge reserves being built up in Britain for D-Day, stands by to be flown to combat units as replacements, May 25, 1944. (Photo by AP Photo)