Competitors make their way up Heartbreak Hill during the 2022 City to Surf on August 14, 2022 in Sydney, Australia. (Photo by Jenny Evans/Getty Images)

Polar bear twins make their first public appearance with their mother “Freedom” at Ouwehands Zoo Rhenen, in Rhenen, The Netherlands, 19 February 2015. The twins, who were born in November 2014, have not been named because their gender has not yet been determined. (Photo by Bart Maat/EPA)

A member of the “Exit Point” amateur rope-jumping group jumps from a 44-metre high (144-feet high) waterpipe bridge in the Siberian Taiga area outside Krasnoyarsk, September 28, 2014. Fans of rope-jumping, a kind of extreme sport involving a jump from a high point using an advanced system of amortization including mountaineering and rope safety equipment, attended the Golden Autumn group's jumping season. (Photo by Ilya Naymushin/Reuters)

Animal rights activists covered with fake blood sit on the floor during a protest against the use of animals in research to mark World Day for Animals in Laboratories in central Madrid April 24, 2014. The sign reads, “How many rabbits do your shampoo kill?”. (Photo by Andrea Comas/Reuters)

In this Thursday, May 8, 2014 photo, guests look down from the Tilt!, a new tourist attraction that provides guests a unique view of the downtown area from the 94th floor of the John Hancock Building, after it was unveiled in Chicago. People hold onto handrails as the glass and steel facade tilts forward 30 degrees. (Photo by Ashlee Rezin/AP Photo/Sun-Times Media)

An injured national guard officer is carried away by comrades outside the parliament building in Kiev, Ukraine, August 31, 2015. Nearly 90 people were wounded and several of them were in a serious condition on Monday after several explosive devices were thrown from crowds in front of the Ukrainian parliament building in Kiev, the interior minister said in a Tweet. (Photo by Valentyn Ogirenko/Reuters)

The NASA Extreme Environment Mission Operations (NEEMO) 21 mission began on July 21 as an international crew of aquanauts splashed down to the undersea Aquarius Reef Base, located 62 feet below the surface of the Atlantic Ocean in the Florida Keys National Marine Sanctuary. The NEEMO 21 crew will perform research both inside and outside the habitat during a 16-day simulated space mission. During simulated spacewalks carried out underwater, they will evaluate tools and mission operation techniques that could be used in future space missions, including journeys to Mars. (Photo by Karl Shreeves/NASA)

These images show off some of the world's most majestic creatures silhouetted against the beautiful rising and setting sun. The vibrant pictures feature a variety of animals in the wild and were taken by a host of photographers at locations around the world. The striking images all have one thing in common: the photographers' awe-inspiring ability to perfectly capture the silhouettes of earth's beautiful creatures. Here: a blue wildebeest moves through grassland at dawn with the sun in the background in Mara Naboisho Conservancy, Kenya, Africa. (Photo by Renato Granieri/Caters News/Ardea)