Passengers climb to board an overcrowded train at a railway station in Dhaka August 8, 2013. Millions of residents in Dhaka are travelling home from the capital city to celebrate the Muslim Eid al-Fitr holiday, which marks the end of the Muslim holy fasting month of Ramadan. (Photo by Andrew Biraj/Reuters)

Santa, a dog abandoned two days before Christmas, is looked after by Charlene Gunner at Battersea Dogs and Cats Home on December 27, 2012 in London, England. The home was founded 150 years ago and has rescued, reunited and rehomed over three million dogs and cats. The average stay for a dog is just 28 days although some stay much longer. Around 550 dogs and 200 cats are provided refuge by Battersea at any given time. (Photo by Peter Macdiarmid)

Lady officers of the Philippine National Police force show the taped muzzle of their guns at a police camp in Taguig City, south of Manila, Philippines, 22 December 2014. Law enforcement units all over the country held a ceremonial taping of firearms as a counter measure against cases of indiscriminate firing and illegal discharge of service weapons during the upcoming Christmas and New Year celebrations. (Photo by Francis R. Malasig/EPA)

The Ivanpah Solar Electric Generating System is seen in an aerial view on February 20, 2014 in the Mojave Desert in California near Primm, Nevada. The largest solar thermal power-tower system in the world, owned by NRG Energy, Google and BrightSource Energy, opened last week in the Ivanpah Dry Lake and uses 347,000 computer-controlled mirrors to focus sunlight onto boilers on top of three 459-foot towers, where water is heated to produce steam to power turbines providing power to more than 140,000 California homes. (Photo by Ethan Miller/Getty Images)

The sun catches on the panels of a 1928 Rolls Royce Phantom at Northington Grange, the summer home of the Grange Park Opera, on April 16, 2011 near Winchester, England. The English Heritage Grade 1 listed Greek Revival style property was the setting for the inter-war Rolls Royce20-Ghost Club members which was founded in 1949 by a group of owners of vintage Rolls Royce cars. (Photo by Matt Cardy/Getty Images)

Christopher Tubbs embraces his wife Sarah after arriving home during the homecoming of the USS Enterprise at the Norfolk Naval Station July 15, 2011 in Norfolk, Virginia. In its 184 days away from Norfolk, the USS Enterprise cruised nearly 60,000 miles while supporting operations in Afghanistan and Iraq. (Photo by Win McNamee/Getty Images)

Emily Hasler, an English Heritage employee at Charles Darwin's home, Down House, cleans a rabbit bone in his old study on April 2, 2011 in Downe, England. Staff at the house are cleaning and preparing the property ahead of their peak visitor season. The house contains the study where Darwin wrote “On the Origin of Species”, as well as family rooms and an extensive garden that inspired the renowned scientist. (Photo by Oli Scarff/Getty Images)

A young girl plays on the glass bottom platform of the Oriental Pear TV Tower as she travels with her family on the second day of the Chinese Lunar New Year holiday, also known as Spring Festival, in Shanghai, China on February 18, 2018. Some 287 million tourists travelled in China during the first four days of the week-long Chinese Lunar New Year holiday, up 11.1 percent from the same period last year, new data showed Sunday. (Photo by Imaginechina/Rex Features/Shutterstock)