Hemispheric color differences on Saturn's moon Rhea are apparent in this false-color view from NASA's Cassini spacecraft in this March 2, 2010 file photo. (Photo by Reuters/NASA/JPL/SSI)

Lightning streaks across the sky as lava flows from a volcano in Eyjafjallajokul April 17, 2010. (Photo by Lucas Jackson/Reuters)

Seljalandsfoss waterfall, located in Iceland. Seljalandsfoss is one of the most famous waterfalls of Iceland. This waterfall of the river Seljalandsá drops 60 metres (200 ft) over the cliffs of the former coastline. It's possible to go behind the waterfall. (Photo by HotSpot Media)

A group of colorful row houses are reflected on to the top of a black car parked on 3600 block of N street in the Georgetown section of Washington DC, February 16, 2017. (Photo by John McDonnell/The Washington Post)

Britain's Princess Elizabeth clasps her hands in sympathy as Sergeant Jean Bayliss faints at her feet during an inspection of the guard of honour of the Women's Royal Army Corps at Shrewsbury Castle, Shropshire, on July 6, 1949. (Photo by AP Photo)

The singing group The D-Day Darlings take part in the unveiling ceremony of a permanent war memorial, created by artist and writer Fabian Peake, at St Pancras International railway station in London, Britain, November 8, 2018. (Photo by Peter Nicholls/Reuters)

A woman walks inside a building in downtown Havana, Cuba April 21, 2016. (Photo by Alexandre Meneghini/Reuters)