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)

Tara West signals to her partner Natalie Cook during the Bronze final match during the Australian Beach Volleyball Championships at Glenelg Beach on March 13, 2011 in Adelaide, Australia.

ESA astronaut Tim Peake posted this stunning image on his social media channels, commenting: “Station passed through magnificent aurora Australis last night”. Tim is set to return to Earth on 18 June 2016, bringing his six-month Principia mission to the ISS to an end. During his stay he performed more than 30 scientific experiments for ESA and taking part in numerous others from ESA's international partners. ESA and the UK Space Agency have partnered to develop many exciting educational activities around the Principia mission, aimed at sparking the interest of young children in science and space. (Photo by Tim Peake/ESA/NASA)

A disabled child is buried up to his neck in sand during the partial solar eclipse in belief its rays can heal, in Karachi, Pakistan, 25 October 202. A partial solar eclipse occurs when a portion of the Earth is engulfed by the shadow (penumbra) cast by the Moon as it passes between our planet and the Sun in imperfect alignment. During this eclipse - the first of the decade – the Moon appears to cover the Sun, leaving the Sun's halo as a visible rim forming an annulus, popularly known as the 'ring of fire. (Photo by Shahzaib Akber/EPA/EFE/Rex Features/Shutterstock)

Charlene Wittstock (L) and Prince Albert II of Monaco (R) attend the singles Final match between Rafael Nadal of Spain and Roger Federer of Switzerland on day nine of the Monte Carlo Masters Series tennis tournament. (Photo by Pascal Le Segretain/Getty Images). 2008

Grace Chon has put together a series of portraits featuring her 10-month-old son and her rescue dog. In each picture, the dog and baby are wearing matching apparel with party hats, baseball caps and sunglasses, adding fun elements to these adorable portraits.

Female indigenous players vie for the ball during the final match of Peladao, the amateur football tournament, in Manaus, Amazonas state, Brazil, on November 24, 2013. Peladao is known as the biggest amateur football tournament in the world, with more than 1000 teams competing in various categories since 1973. The indigenous category was created in 2005 and eight teams participated this year. (Photo by Yasuyoshi Chiba/AFP Photo)

Photographer Carlos Barria holds a print of a photograph he took in 2005, as he matches it up at the same location 10 years on, in Lafitte, south of New Orleans, United States, August 16, 2015. The print shows Tyler Teal cleaning up his home, September 14, 2005, after Hurricane Katrina struck. In 2005, Hurricane Katrina triggered floods that inundated New Orleans and killed more than 1,500 people as storm waters overwhelmed levees and broke through floodwalls. (Photo by Carlos Barria/Reuters)