The fourth annual BigPicture Natural World Photography Competition aims to celebrate the diversity of life on Earth, and encourages people to protect and conserve it. Here: “The Salmon Catchers”. Terrestrial Wildlife. To capture this view of a mother grizzly bear and her cub, photographer Peter Mather set up a camera trap on a log that he knew the bears tended to traverse while fishing for salmon, in the Yukon River watershed in Canada. (Photo by Peter Mather/BigPicture Natural World Photography Competition 2017)

These beautiful shots may look like works of modern art – but they are actually close-ups of chemical reactions. The works were snapped with the help of a group of scientists from the University of Science and Technology of China (USTC) in Anhui, China. Here: Zinc reacting with lead nitrate in a soft gel to form lead crystals. (Photo by Yan Liang/Caters News)

Believers burn dried oak branches, which symbolizes the Yule log, on Orthodox Christmas Eve in front of the St. Sava temple in Belgrade, Serbia, January 6, 2016. Serbian Orthodox believers celebrate Christmas on January 7, according to the Julian calendar. (Photo by Marko Djurica/Reuters)

Participants hold smoke flares as they slide down along a chute to cross a pool of water and foam during the “Letniy Gornoluzhnik” (Summer mountain puddle rider) festival at the Bobroviy Log Fun Park near the Siberian city of Krasnoyarsk, Russia, August 21, 2016. (Photo by Ilya Naymushin/Reuters)

Wildlife photographer Kevin Fleming has covered the world as a photographer for National Geographic and has been recognized America’s Best Observer by Readers Digest. His assignments have taken him into war and famine in Somalia, to the Mediterranean for a re-creation of the voyage of Ulysses and put him on a dogsled crossing the Canadian arctic. Now Kevin is working on his 27th book. Here: Red fox kits look out from a hollow log. (Photo by Kevin Fleming)

A cow moves past a burning car that, according to fire officials, caught fire by an electrical short circuit after it was stuck in a water-logged road following heavy rains in Ahmedabad, India, July 11, 2022. (Photo by Amit Dave/Reuters)