A child coughs as migrants and refugees run away after Macedonian police fired tear gas at hundreds of Iraqi and Syrian migrants who tried to break through the Greek border fence in Idomeni, on February 29, 2016. Greek police said more than 6,000 people were massed at the border, in a buildup triggered by Austria and Balkan states capping the numbers of migrants entering their territory. (Photo by Louisa Gouliamaki/AFP Photo)

Revellers use water guns as they participate in a water fight during Songkran Festival celebrations at Kowloon City district, known as Little Thailand as there is large number of restaurants and shops run by Thais, in Hong Kong April 12, 2015. The Songkran festival, also known as the water festival, marks the start of Thailand's traditional New Year and is believed to wash away bad luck. (Photo by Tyrone Siu/Reuters)

In this artist's impression supplied by the ESO (European Southern Observatory) on April 25, 2007, the planetary system around the red dwarf, Gliese 581, is pictured showing what astronomers believe is the most earth like planet found outside our solar system to date. Using the ESO 3.6-m telescope in Chile, astronomers have uncovered the planet which could have water running on its surface. The planet orbits the faint star Gliese 581, which is 20.5 light-years away in the constellation Libra. (Photo by ESO via Getty Images)

A man wearing a native costume named “Woman Carrying Husband” poses ahead of the Carnival in Sostanj January 15, 2015. Slovenians and members of various ethnological groups celebrate the annual carnival, also known locally as Pust, by wearing traditional masks and costumes to symbolically “chase away” the winter. Prust runs from February 7 to 17 this year. (Photo by Srdjan Zivulovic/Reuters)

DJI Phantom 3 Severe Crash - Train Bridge

The competition, which is run by the Royal Observatory Greenwich in association with BBC Sky at Night Magazine, is now in its sixth year and has received over 2,500 entries. Photo: Centre of the Heart Nebula by Ivan Eder (Hungary). Situated 7500 light years away in the “W”-shaped constellation of Cassiopeia, the Heart Nebula is a vast region of glowing gas, energized by a cluster of young stars at its centre. The image depicts the central region, where dust clouds are being eroded and moulded into rugged shapes by the searing cosmic radiation. (Photo by Ivan Eder)