Starting in September, Indonesia's Mount Sinabung began erupting yet again. In the days that followed, ash and smoke were shot into the air multiple times. As a result, nearby towns turned gray from repeated blows by the volcano. Photo: A man uses his mobile phone as Mount Sinabung continues to erupt, with hot smoke spewing from the volcano, in the Karo district on the north of Indonesia's Sumatra island on November 18, 2013. Officials said a week ago at more than 5,000 people had fled their homes since the volcano erupted early this month. (Photo by Sutanta Aditya/AFP Photo)

Wounded people walk after clashes with riot police in central Kiev February 18, 2014. Ukrainian riot police advanced on the heart of 12-week-old protests against President Viktor Yanukovich on Tuesday and security forces set a deadline to end disturbances after at least five protesters were reported killed in a day of clashes. (Photo by Vlad Sode/Reuters)

Trainees of the Tianjiao Special Guard/Security Consultant bodyguard training camp watch their instructor use a scarf to cover a student's head during a demonstration of close-quarter combat skills at a special course on flight safety inside a scale model of a passenger jet at a flight attendant training centre on the outskirts of Beijing, March 18, 2014. Inspired by the missing Malaysia Airlines Flight MH370, the company wanted to emphasize the importance of aviation safety by teaching their trainees emergency evacuation procedures and close-quarter combat skills to handle situations such as natural disasters and plane hijacks, according to the company. (Photo by Jason Lee/Reuters)

Amphibious assault vehicles of the South Korean Marine Corps throw smoke bombs as they move to land on shore during a U.S.-South Korea joint landing operation drill in Pohang March 31, 2014. The drill is part of the two countries' annual military training called Foal Eagle, which began on February 24 and runs until April 18. (Photo by Kim Hong-Ji/Reuters)

The Al-Gaffal is an annual long-distance race between crews sailing 60-ft. traditional wooden boats called dhows and takes place in the Persian Gulf, between the island of Sir Bu Nair, near the Iranian coast and the Gulf emirate of Dubai. Photo: Traditional wooden boats, or dhows, compete at sunrise during the Al Gaffal race, a long-distance dhow sailing race, near Sir Bu Nuayr, near Sharjah May 18, 2014. (Photo by Martin Dokoupil/Reuters)

Nestled among the cocoa plantations of western Ivory Coast is a gold mine that does not feature on any official maps. It is not run by an industrial mining company, nor does it pay taxes to the central government. The unlicensed mine is a key part of a lucrative business empire headed by the deputy commander of the West African nation's elite Republican Guard, United Nations investigators allege. Here: A gold prospector sits and eats close to a soldier at a gold mine near the village of Gamina, in western Ivory Coast, March 18, 2015. (Photo by Luc Gnago/Reuters)

A Japanese Ground Self-Defense Force Type 92 Mine sweeping vehicle fires a rocket behind a Type 74 armoured tank during an annual training session, which is based on a scenario to defend or retake islands in Japanese territory, near Mount Fuji at Higashifuji training field in Gotemba, west of Tokyo, August 18, 2015. (Photo by Yuya Shino/Reuters)

European Space Agency astronaut Tim Peake will return home after a six-month long mission on the International Space Station,on June 18, 2016. Peake was the first British ESA astronaut to visit the ISS and captured hundreds of photographs of the Earth during his mission. Here: “Lots of sun-glint right now during our whole orbit – we haven't seen a sunset for over 3 days”, he wrote. (Photo by Tim Peake/ESA/NASA)