An Indonesian woman watches an eruption from the Mount Sinabung volcano from Tiga Pancur village, in Karo in North Sumatra on November 3, 2017. Sinabung roared back to life in 2010 for the first time in 400 years. After another period of inactivity it erupted once more in 2013, and has remained highly active since. (Photo by Ivan Damanik/AFP Photo)

A student attending a winter military camp reacts during a training session in Ansan, south of Seoul January 3, 2013. Hundreds of students between 11 and 17 years old attend winter boot camp training courses every year. The winter courses range from 4 to 14 days at the Blue Dragon Camp run by retired marines, which also offers summer boot camp for students. (Photo by Kim Hong-Ji/Reuters)

Isabel Schmalenbach, an environmental scientist with the Helgoland Biological Institute (Biologische Anstalt Helgoland), part of the Alfred Wegener Institute for Polar and Marine Research, holds a one-year old baby European lobster (Homarus gammarus) raised at the institute on August 3, 2013 on Helgoland Island, Germany. Later in the day Schmalenbach and her colleagues released a total of 415 one-year old lobsters into the North Sea as part of an effort to repopulate the lobster population around Helgoland (also called Heligoland). In the 19th century local fishermen caught up to 80,000 lobsters a year in the surrounding waters, combined with the heavy allied bombing of the island during and after World War II, as well as other environmental factors, decimated the lobster population. (Photo by Sean Gallup)

Members of the 1st Tennessee wait to take part in in a demonstration of a battle during ongoing activities commemorating the 150th anniversary of the Battle of Gettysburg, Friday, June 28, 2013, at at Bushey Farm in Gettysburg, Pa. Union forces turned away a Confederate advance in the pivotal battle of the Civil War fought July 1-3, 1863, which was also the war's bloodiest conflict with more than 51,000 casualties. (Photo by Matt Rourke/AP Photo)

Tourists look at other festival-goers playing in the mud during the Boryeong Mud Festival at Daecheon beach in Boryeong, about 190 km (118 miles) southwest of Seoul, July 19, 2013. About 2 to 3 million domestic and international tourists visit the beach during the annual mud festival, according to the festival organisers. (Photo by Lee Jae-Won/Reuters)

An Indian bride, sits during a mass marriage of 162 Muslim couples in Ahmadabad, India, Sunday, March 3, 2013. Mass marriages in India are organized by social organizations primarily to help the economically backward families who cannot afford the high ceremony costs as well as the customary dowry and expensive gifts that are still prevalent in many communities. (Photo by Ajit Solanki/AP Photo/LaPresse)

NASA says it could be another 20 years before humans touch down on Mars, but in a sense, the Mars Society has been exploring the red planet for more than a decade – in Utah. Photo: Csilla Orgel, a geologist of Crew 125 EuroMoonMars B mission, makes her way back to the Mars Desert Research Station (MDRS) in the Utah desert March 3, 2013. The MDRS aims to investigate the feasibility of a human exploration of Mars and uses the Utah desert's Mars-like terrain to simulate working conditions on the red planet. Scientists, students and enthusiasts work together developing field tactics and studying the terrain. All outdoor exploration is done wearing simulated spacesuits and carrying air supply packs and crews live together in a small communication base with limited amounts of electricity, food, oxygen and water. Everything needed to survive must be produced, fixed and replaced on site. (Photo by Jim Urquhart/Reuters)

The main church in the town of San Damian Texoloc, Mexico stands in front of the Popocatepetl volcano as is spews ash and vapor early Tuesday, July 9, 2013. Last Saturday, Mexico's National Center for Disaster Prevention raised the volcano alert from Stage 2 Yellow to Stage 3 Yellow, the final step before a Red alert, when possible evacuations could be ordered after the Popocatepetl volcano spit out a cloud of ash and vapor 2 miles (3 kilometers) high over several days of eruptions. (Photo by J. Guadalupe Perez/AP Photo)