Marines finish a 10 kilometer training hike carrying 55 pound (25 kg) packs during Marine Combat Training (MCT) on February 22, 2013 at Camp Lejeune, North Carolina. Since 1988 all non-infantry enlisted male Marines have been required to complete 29 days of basic combat skills training at MCT after graduating from boot camp. MCT has been required for all enlisted female Marines since 1997. About six percent of enlisted Marines are female. (Photo by Scott Olson/AFP Photo)

A young YPJ recruit (in pink) arrives to the training base for her first day in training near Derek City, Syria. The YPJ schedule is demanding and requires discipline – new soldiers in training get about 6 hours of sleep a night and wake up at 4 AM to begin exercising; afterwards, their day consists of a full schedule of drills and classroom lessons. Before joining the YPJ many of the girls had never participated in physical activity or sports before. (Photo by Erin Trieb/NBC News)

Drivers push cars to gas station during “oil crisis”, Roslindale, Boston, Massachusetts, 1973. (Photo by Spencer Grant/Getty Images)

Image of the Clouds taken in August 2014 by astronauts on board the International Space Station (ISS). A year from space photographs of hurricanes, typhoons and meteorite craters show an astronauts-eye view of our planet from hundreds of miles above the earth. The illuminating images were taken by astronauts onboard the International Space Station (ISS) over the course of 2014. (Photo by NASA/SPL/Barcroft Media)

Performers walk past a light installation “Butterfly Effect” designed by Japan artist Masamichi Shimada, at the Battersea Power Station in London, Thursday, January 25, 2024. The Light Festival involved seven light installations from British and international artists at Battersea Power Station, which illuminated the winter evenings between Jan. 25 and Feb, 25. (Photo by Kin Cheung/AP Photo)

A model presents a creation at a metro station during a show opening the Moscow Fashion Week in Moscow, Russia on October 22, 2019. (Photo by Evgenia Novozhenina/Reuters)

A photo taken from the International Space Station shows Hurricane Lane in the early morning hours near Hawaii, August 22, 2018. (Photo by Courtesy @astro_ricky/NASA/Handout via Reuters)

Brazen seagulls, pigeons and starlings bask in the afternoon sun undeterred by a plastic Owl bird scarer on the roof of Liverpool Coastguard Station at Crosby on January 13, 2012 in Liverpool, England. (Photo by Christopher Furlong/Getty Images)