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)

Members of the Jordanian police women's team attend the 7th Annual Warrior Competition at the King Abdullah Special Operations Training Center in Amman April 22, 2015. Thirty-eight teams from 18 countries are participating in the competition to test their military skills. (Photo by Muhammad Hamed/Reuters)

Francisca Gomez stands at an entrance to her home, a cave where she has been living for the past 50 years, in the mountains on the outskirts of Chusmuy, Honduras April 21, 2015. The 75-year old widow receives help from neighbors and friends and she makes a little money by selling wood she collects, according to a local newspaper. (Photo by Jorge Cabrera/Reuters)

Armed man stand at entrance of the naval headquarters in Sevastopol, March 19, 2014. Around a dozen Ukrainian servicemen, unarmed and in civilian clothes, walked out of the Ukrainian naval headquarters in the Crimean port of Sevastopol on Wednesday after it was taken over by pro-Russian forces, a Reuters witness said. (Photo by Baz Ratner/Reuters)

A member of a local swimming club holds a Russian national flag as he dives in at the start of a 24-hour swimming marathon near the western Siberian city of Barnaul March 29, 2014. Thirty members of the club will swim in turn during the event, held to mark Crimea becoming part of Russia, local media reported. (Photo by Andrei Kasprishin/Reuters)

Cars sit abandoned in a former shopping centre in the United Nations buffer zone in central Nicosia March 12, 2014. The cars were imported from Japan to be sold at a Toyota dealership. They were stored here during the 1974 conflict and have not been moved since. (Photo by Neil Hall/Reuters)

Netapp Endura team rider Slovenian Blaz Jarc (R) crashes into Katusha team rider Russian Viacheslav Kuznetsov (ground) during the 112th Paris Roubaix cycling race, in Roubaix, France, 13 April 2014. (Photo by Nicolas Bouvy/EPA)

Macro or Micro? Scientists’ pictures baffle our sense of scale. It began when Stephen Young, a geography professor at Salem State University in Massachusetts, tricked his biologist colleague Paul Kelly into thinking a satellite image was one of his electron microscope scans. Can you guess whether they are close-up or very far away? (Photo by Paul Kelly)