Space Shuttle Discovery is towed from the shuttle landing facility to the orbiter processing facility at Kennedy Space Center on April 20, 2010 in Cape Canaveral, Florida. Discovery's landing attempts at KSC were scrubbed yesterday due to unacceptable weather conditions. Discovery is returning from a successful mission to the International Space Station. (Photo by Matt Stroshane/Getty Images). CAPE CANAVERAL, FL – APRIL 20 2010

Masked revellers pose during the Venice Carnival in Venice, Italy February 11, 2017. The Venice carnival in the historical lagoon city attracts people from around the world. (Photo by Tony Gentile/Reuters)

Christ the Redeemer is seen from the Vista Chinesa (Chinese View) during sunrise in Rio de Janeiro, Brazil, May 4, 2016. Rio de Janeiro is a marvel and a mess all at once. When it hosts the first ever Olympics in South America, starting Aug. 5, visitors will see a city whose stunning topography – stark, verdant mountains loom over packed and playful beaches – competes only with the drama of daily life here. (Photo by Ricardo Moraes/Reuters)

A Muslim Shi'ite boy carries a toy gun while standing next to a picture of Hezbollah leader Sayyed Hassan Nasrallah as he takes part in a march organised by Hezbollah during a re-enactment of the battle of Kerbala during a mourning process, ahead of the day of Ashura, in Saksakieh village, southern Lebanon, October 18, 2015. Ashoura, the most important day in the Shi'ite calendar, commemorates the death of Imam Hussein, grandson of the Prophet Mohammad, in the 7th century battle of Kerbala. (Photo by Ali Hashisho/Reuters)

An ice covered entrance door to the international gene bank Svalbard Global Seed Vault (SGSV) near Longyearbyen on Spitsbergen, Norway, October 20, 2015. Two consignments of crop seeds will be deposited next year in a “doomsday vault” built in an Arctic mountainside to safeguard global supplies. The vault, which opened on the Svalbard archipelago in 2008, is designed to protect crop seeds, such as beans, rice and wheat against the worst cataclysms of nuclear war or disease. (Photo by Anna Filipova/Reuters)

In this Wednesday, January 7, 2015 photo, a Sri Lankan Catholic devotee Rita Anthony kisses her rosary as she prays inside her house in Colombo, Sri Lanka. The Vatican has said that it hopes that Sri Lanka's Christians can play a role in helping heal the wounds of the island nation's bloody 25-year civil war, when the Tamil Tiger rebels fought to create a separate homeland in the north for the minority Tamils, who are mostly Hindu. The war came to a bloody end in 2009, but many Tamils say they feel forgotten by the central government, which is dominated by the country's ethnic Sinhala majority, which is overwhelmingly Buddhist. Sri Lanka's Christians come from both the Tamil and the Sinhala communities, making them a natural bridge between the two sides. (Photo by Eranga Jayawardena/AP Photo)

A National Army of Colombia soldier, who was wounded by a mine, swims at a pool in Bello, municipality of Antioquia, March 25, 2015. (Photo by Fredy Builes/Reuters)

During the spring harvest season, a group of traditional Malaysian honey hunters travel to the rainforest near the Thai border to collect honeycombs from giant bees – and risk their lives climbing 200ft trees. Here: Bees are sensitive to light, which makes them follow the glowing embers down to the ground. (Photo by Hasnoor Hussain/The Guardian)