Mount Sinabung is seen during an eruption from Surbakti village in Karo, North Sumatra, Indonesia, April 20, 2015. The local government is preparing the relocation of residents from three of the villages that were destroyed. (Photo by Tibta Pangin/Getty Images/Anadolu Agency)

A prototype battery-powered plane, called Greased Lightning or GL-10 is pictured flying at NASA's Langley Research Center in this undated handout photo obtained by Reuters May 1, 2015. The plane, which has 10 engines and can take off like a helicopter and fly efficiently like an aircraft, is currently in the design and testing phase. (Photo by Reuters/NASA)

Beachgoers watch the detonation of a 500 pound British bomb on the beach on May 19, 2014 in Wassenaar, Netherlands. The bomb was dropped by the British allied forces during the second world war over nearby Leiden where it was found on a building site. (Photo by Michel Porro/Getty Images)

An Indonesian man (C), one of two to be publicly caned for having s*x, is caned in Banda Aceh on May 23, 2017. .The pair, aged 20 and 23, were found guilty of having broken sharia rules in conservative Aceh province – the only part of Indonesia that implements Islamic law – and sentenced to 85 strokes of the cane each. (Photo by Chaideer Mahyuddin/AFP Photo)

Nursery plants are seen placed in people's seats during a rehearsal as Barcelona's Gran Teatre del Liceu opera reopens its doors with a concert for plants, to raise awareness about the importance of an audience after the coronavirus lockdown, in Barcelona, Spain on June 22, 2020. The Gran Teatre del Liceu reopens its doors, in which the 2,292 seats of the auditorium will be occupied on this occasion by plants. It will be on 22 June, broadcast live online, when the UceLi Quartet string quartet performs Puccini's “Crisantemi” for this verdant public, brought in from local nurseries. (Photo by Nacho Doce/Reuters)

An elephant “kisses” a visitor during a show at an elephant training school in Xishuangbanna, Yunnan province, April 18, 2015. Some 16 elephants live at the school and give four 30-minute performances everyday for visitors. (Photo by Wong Campion/Reuters)

People dance Tuesday, April 28, 2015, in Baltimore. Maryland's governor vowed there would be no repeat of the looting, arson and vandalism that erupted Monday in some of the city's poorest neighborhoods. (Photo by Matt Rourke/AP Photo)

Party-goers partake in a festival better known as Holi One, during International Workers Day in Johannesburg, South Africa, 01 May 2015. The colour festival promotes togetherness as well as colourness in everday life. May Day is observed worldwide every year on 01 May. (Photo by Kevin Sutherland/EPA)