A small section of the expanding remains of the Veil Nebula, a massive star that exploded about 8,000 years ago. The entire nebula is 110 light-years across, covering six full moons on the sky as seen from Earth, and resides about 2,100 light-years away in the constellation Cygnus, the Swan. (Photo by Reuters/NASA/ESA/Hubble)

A woman looks out of her house with a decorated doorway during Corpus Christi day in Zahara de la Sierra, southern Spain, May 29, 2016. The village of Zahara de la Sierra celebrated the feast of Corpus Christi (or Body of Christ in Latin) by covering the streets and facades of houses with the branches of trees and grass. (Photo by Jon Nazca/Reuters)

A female swimmer reacts after finishing the competition in a pool carved from thick ice covering the Songhua River during the Harbin Ice Swimming Competition in the northern city of Harbin, Heilongjiang province, January 5, 2016. The swimming competition was held on the official launch day of the Harbin International Ice and Snow Sculpture Festival. (Photo by Aly Song/Reuters)

A sledding dog is covered in ice after spending the night in the open air with his musher at the polar base of Val-Cenis, as they ready for the next stage of the 12th edition of “La Grande Odyssee” sledding race across the Alps on January 17, 2016 in Val Cenis Lanslevillard. (Photo by Jean-Philippe Ksiazek/AFP Photo)

“Winter shapes, Moscow river”. Moscow river at this part is never covered by ice. When the temperature is very low it's possible to see a strong fog. Morning light and pipes of the oli factory creates a fantastic landscape. Photo location: Moscow, Russia. (Photo and caption by Sergey Rumyantsev/National Geographic Photo Contest)

Qiandao Lake (Chinese: 千島湖, lit. Thousand Island Lake), a man-made lake located in Chun'an County, Zhejiang, China, formed after the completion of the Xin'an River hydroelectric station in 1959. 1,078 large islands dot the lake and a few thousand smaller ones are scattered across it. The lake covers an area of 573 km² and has a storage capacity of 17.8 km³. The islands in the lake cover about 86 km²

A large storm cloud covers the Sydney CBD on March 5, 2014 in Sydney, Australia. A severe thunderstorm warning was issued for the Sydney metropolitan area late this afternoon with heavy rainfall due to cause flash flooding in areas. (Photo by Cassie Trotter/Getty Images)

Women grieves near a bodies covered by tarp at the site of a landslide in Xinmo village in Maoxian County in southwestern China's Sichuan Province, Sunday, June 25, 2017. Crews searching through the rubble left by a landslide that buried a mountain village under tons of soil and rocks in southwestern China on Saturday found bodies, but more than 100 people remained missing. (Photo by Ng Han Guan/AP Photo)