A Macedonian police officer hits a stranded migrant attempting to cross the Greek-Macedonian border, near Gevgelija, Macedonia December 2, 2015. Picture taken from the Greek side of the border. (Photo by Alexandros Avramidis/Reuters)

Anti-Heathrow expansion activists walk through the “Grow Heathrow” protest camp in the village of Sipson near to Heathrow Airport, west London Britain December 7, 2015. (Photo by Peter Nicholls/Reuters)

A woman washes her dishes outside the temporary shelter built near the houses damaged during an earthquake earlier this year, in Bhaktapur, Nepal December 28, 2015. (Photo by Navesh Chitrakar/Reuters)

Migrating starlings fly in formation near the southern Israeli town of Rahat February 2, 2015. The phenomenon, known as murmuration, is most common during the winter months. (Photo by Nir Elias/Reuters)

A Ukrainian serviceman wearing a new year's hat waves at his comrades while standing beside his tank near Debaltseve, eastern Ukraine, February 8, 2015. (Photo by Gleb Garanich/Reuters)

North Korean children wave to people on a Chinese tourist boat on the banks of Yalu River near the Chongsong county of North Korea, opposite the Chinese border city of Dandong, May 8, 2011. (Photo by Jacky Chen/Reuters)

This Sunday, September 7, 2014 photo provided by Rachel Kirk shows smoke from a fire rising above Little Yosemite Valley near Yosemite National Park, Calif. (Photo by Rachel Kirk/AP Photo)

A hot air balloon floats past an almost full rising moon on a warm fall evening near Encinitas, California October 5, 2014. (Photo by Mike Blake/Reuters)