Afghan militia men stand near to the dead body of a beheaded Islamic State group loyalist in the Achin district of Nangarhar province east of Kabul, Afghanistan, Sunday, December 27, 2015. An Afghan official says fighters for the Islamic State group and a militia controlled by a prominent lawmaker have beheaded a total of eight men in tit-for-tat revenge killings in the eastern border province of Nangarhar. (Photo by Mohammad Anwar Danishyar/AP Photo)

Black-headed gulls sit on pickets at a riverside in Tokyo, Japan, December 27, 2015. (Photo by Toru Hanai/Reuters)

Jassen Todorov, 40, from San Francisco is a professor of music at San Francisco State University, but he took to helicoptering in his spare time. While he was content to keep the panoramic views he witnessed to himself, Todorov has now paired his passion for flying with photography to capture some of the United States’ undiscovered vistas. Here: Grand Prismatic Spring, Yellowstone, Wyoming. (Photo by Jassen Todorov/Caters News)

An airplane crosses a nearly full-moon on its way to Los Angeles International Airport near Whittier, Calif., Thursday, December 24, 2015. Not since 1977 has a full moon dawned in the skies on Christmas. (Photo by Nick Ut/AP Photo)

Thousands flock to Bondi Beach for the traditional expats Christmas Day celebration in Sydney, Australia, 25 December 2014. Expats of all nationalities have been flocking to Bondi Beach for Christmas Day for many years. (Photo by Dean Lewins/EPA)

Ultra Orthodox Jews look at the body of an alleged Palestinian assailant in Jerusalem Saturday, December 26, 2015. According to a police spokeswoman, policemen approached a man who drew their suspicions just outside the Old City for following a pair of Jewish worshippers. Then he pulled out a knife and tried to stab one of them, officers opened fire and killed the assailant. (Photo by Mahmoud Illean/AP Photo)

A worker adds gunpowder into paper cylinders to make fireworks at a factory in Bocaue town, Bulacan province, Philippines, December 26, 2015. (Photo by Romeo Ranoco/Reuters)

Internally displaced Syrian children stand at the entrance of their makeshift shelter that is an underground cave in Om al-Seer, southern Idlib countryside, Syria December 26, 2015. (Photo by Khalil Ashawi/Reuters)