A woman smokes a mask bong on the final day of Hempfest, Seattle's annual gathering to promote the legalization of marijuana, on August 17, 2014. (Photo by Jordan Stead/Seattlepi.com)

Participants hang from ropes as they learn how to use safety gears at an experience centre for construction safety training in Beijing, September 5, 2014. The centre which opened in June 2014 was established to educate workers about construction safety. According to the centre, about 1,000 construction workers undergo 3-hour classes which comprises of 33 modules every month. (Photo by Kim Kyung-Hoon/Reuters)

All throughout history of mankind people were fascinated by time, its flow, and how to measure it. Thus, the science of horology can into being, as people invented more and more sophisticated ways of measuring the passage of time. Truly, it’s one of the most profound characteristics of being a human, to feel and to ponder the meaning of time, its properties, and will we ever be able to move through it, not with it. Now, however, horology is mainly referred to the art of mechanical watchmaking. (Photo by MB&F)

A participant prepares for the Red Bull Air Race World Championships in Abu Dhabi, United Arab Emirates on February 6, 2017. (Photo by Red Bull Content Pool/SIPA Press/Rex Features/Shutterstock)

Iraqi troops fire artillery towards Islamic State (IS) group jihadists' positions in west Mosul on March 11, 2017 during the ongoing battle to retake the city from the group. (Photo by Aris Messinis/AFP Photo)

Merit: A Night at Deadvlei. The night before returning to Windhoek, we spent several hours at Deadveli. The moon was bright enough to illuminate the sand dunes in the distance, but the skies were still dark enough to clearly see the milky way and magellanic clouds. Deadveli means “dead marsh. The camelthorn trees are believed to be about 900 years old, but have not decomposed because the environment is so dry. (Photo and caption by Beth McCarley/National Geographic Traveler Photo Contest)

Schwarzenegger began weight training at the age of 15. He won the Mr. Universe title at age 20 and went on to win the Mr. Olympia contest seven times. Schwarzenegger has remained a prominent presence in bodybuilding and has written many books and articles on the sport. Schwarzenegger gained worldwide fame as a Hollywood action film icon. He was nicknamed the "Austrian Oak" and the "Styrian Oak" in his bodybuilding days, "Arnie" during his acting career and more recently "The Governator" (a portmanteau of "Governor" and "The Terminator" – one of his best-known movie roles).

“The Red-eyed Treefrog (Agalychnis callidryas) is an arboreal hylid native to Neotropical rainforests in Central America. Red-eyed tree frogs, as their name states, have red eyes with vertically narrowed noses, a vibrant green body with yellow and blue vertically striped sides, and orange or yellow webbed feet and toes”. – Wikipedia. (Photo by Donald Quintana)