A leg of a “diablito” frog (Oophaga sylvatica) is photographed in a laboratory at a laboratory in the zoo of Cali, Colombia, on July 19, 2019. Colombia is the second country with the largest number of amphibians in the world after Brazil. More than 40% of amphibian species worldwide are in danger of extinction. (Photo by Luis Robayo/AFP Photo)

A woman yawns as she sits outside a hospital on a cold winter morning in Srinagar January 3, 2019. (Photo by Danish Ismail/Reuters)

The Aurora Borealis (Northern Lights) is seen in the sky in Ivalo of Lapland, Finland on September 27, 2019. (Photo by Alexander Kuznetsov/Reuters)

A sand carver works on a sculpture during the Sand Sculpture Festival “Dreams” in Ostend, Belgium on June 18, 2019. (Photo by Yves Herman/Reuters)

An annual fire festival is held in Nachikatsuura, Wakayama Prefecture, western Japan, on July 14, 2019. (Photo by Kyodo News via Getty Images)

The Aurora Borealis (Northern Lights) is seen in the sky in Ivalo of Lapland, Finland on September 27, 2019. (Photo by Alexander Kuznetsov/Reuters)

A girl goes to school just before sunrise in Frankfurt, Germany, Wednesday, December 11, 2019. (Photo by Michael Probst/AP Photo)

A fisherman waits to catch fish as he sits atop a stilt in the sea in Koggala, Sri Lanka on July 4, 2019. (Photo by Dinuka Liyanawatte/Reuters)