Three workers demonstrating the different types of gas masks used in mine rescue work. (Photo by Fox Photos/Getty Images). December 1925

Dr. Lisa Ballance (NOAA Fisheries Service) with a curious calf – this is a Type C killer whale, a fish-eater.

U.S. Air Force pilots with the Thunderbirds perform the calypso pass maneuver in F-16 Fighting Falcon aircraft during a practice session prior to the Gunfighter Skies air show at Mountain Home Air Force Base, Idaho, September 19 and released September 24, 2014. (Photo by Tech. Sgt. Manuel J. Martinez/Reuters/US Air Force)

A United States Air Force (USAF) F-15 fighter jet travels at low altitude through the “Mach Loop” series of valleys near Dolgellau, north Wales on June 26, 2018. The Mach Loop valleys, situated between Dolgellau and Machynlleth, are regularly used by the military for operational low flying training which can take place as low as 76 metres from the nearest terrain. The USAF regularly use the loop to practice low-altitude flight, which confuses radar systems. (Photo by Oli Scarff/AFP Photo)

Newly commissioned 2nd lieutenants throw their caps in the air as a team of F-16 Air Force Thunderbirds fly over the 2011 graduating class of the U.S. Air Force Academy on May 25, 2011 in Colorado Springs, Colorado. A total of 1,021 graduates received their diplomas in front of their families and dignitaries at the Academy's Falcon Stadium. (Photo by John Moore/Getty Images)

A woman sits by a fountain in central Moscow, Russia on June 23, 2021. On June 23, 2021, daytime temperature is expected to reach +36°C (96.8°F). An orange weather warning has been issued due to the heat wave. (Photo by Sergei Fadeichev/TASS)

Film technicians at Pinewood Studios set up a miniature air crash sequence for the Jack Gold film “The Medusa Touch”, using scale models of a Boeing 747 and a skyscraper. (Photo by Alan F. Davis/Keystone/Getty Images). 9th August 1977