Former U.S. Vice presidential candidate and Alaska Governor Sarah Palin (R) greets some of the thousands of motorcycle enthusiasts and military veterans participating in 'Rolling Thunder' rally May 29, 2011 in Arlington, Virginia. Although not an official guest, former U.S. Vice presidential candidate and Alaska governor Sarah Palin is expected to participate in today's motorcycle parade from the Pentagon to the National Mall.

In this photo illustration, an endangered Chinese box turtle which hatched at Bristol Zoo is placed on a box of matches on August 12, 2008 in Bristol, England. It weighs just 15 grams and measures around 4cm long whereas an adult box turtle weighs around 800 grams, measures around 16 cm long and can live up to 50 years. Chinese box turtles are hunted for their meat for use in medicine or as pets and have been listed as endangered on the International Union for Endangered Species Red List. (Photo by Matt Cardy/Getty Images)

Golden monkeys play at a conservation base in Shennongjia, central China's Hubei Province, January 26, 2018. The golden monkey conservation base witnessed a snowfall recently. (Photo by Du Huaju/Xinhua/Barcroft Images)

Recycling artist Nicolas Gomez checks the strings of a cello he has made out of an oil barrel for the Orchestra of Recycled Instruments of Cateura, in Cateura, Paraguay February 13, 2015. Saudi Arabia's oil exports have risen in February in response to stronger demand from customers. As OPEC's top producer battles for market share Reuters photographers around the globe have been photographing oil barrels to document how they are utilised once the fuel has been used. (Photo by Jorge Adorno/Reuters)

Second place, Nature: double trapping. Picture taken in the Brazilian Pantanal ... when I downloaded the CF did not want to believe it ... The nature knows we always give magnificent events but sometimes extraordinary. (Photo by Massimiliano Bencivenni/National Geographic Travel Photographer of the Year Contest)

A woman stands at the door of her shanty at a slum in Mumbai, India July 20, 2016. (Photo by Danish Ismail/Reuters)

A girl takes a nap during a Christmas eve mass at a Catholic church on the outskirts of Taiyuan, North China's Shanxi province, December 24, 2016. (Photo by Jason Lee/Reuters)

An Afghan girl makes a pile of unbaked bricks near the road passing through the Shamali Plains, about 10 kilometers (6 miles), west of Bagram, Afghanistan, Wednesay April 9, 2003. Children assist parents in their job to supplement family income. (Photo by Gurinder Osan/AP Photo)