A woman cools off from the extreme heat from an opened fire hydrant in Brooklyn, New York on July 2, 2018. The highest temperature reached 35 degrees Celsius in New York City on Monday as a result of a prolonged heat wave. (Photo by Shannon Stapleton/Reuters)

A guest arrives before the Blumarine show during Milan Fashion Week Spring 2019 in Milan, Italy, September 21, 2018. (Photo by Stefano Rellandini/Reuters)

Revellers enjoy during New Year celebrations in Manchester, England on January 1, 2019. (Photo by Mercury Press)

France's Christian Lavieille and co-pilot Jean-Michel Polato compete with their Proto Dessoude during the first stage of the Dakar Rally 2013 from Lima to Pisco January 5, 2013. (Photo by Jacky Naegelen/Reuters)

“Lobsang and 66 fellow monks were imprisoned in 1959. When released 21 years later, he was one of only three survivors. While in prison his best friend, a rinpoche, died in his arms. Tensin was later discovered to be the reincarnation of that friend. Lobsang said there are so many characteristics of his old friend in the young boy”. (Photo and caption by Phil Borges)

Expedition 44 flight engineer and NASA astronaut Scott Kelly seen inside the Cupola, a special module which provides a 360-degree viewing of the Earth and the International Space Station. Kelly is one of two crew members spending an entire year in space. (Photo by Scott Kelly/NASA)

Subway passengers walk past bronze sculptures representing the Soviet people at the Ploshchad Revolyutsii metro station in Moscow, on November 14, 2012. The station was opened in 1938. (Photo by Kirill Kudryavtsev/AFP Photo)

“Hippo Chase”. As we approached the camp the Selinda Reserve of northern Botswana our boat passed by a hippo resting in the water. I turned around to look back at the boat's wake and saw the hippo charging after us! The hippo must've been tired from an all-nighter because he was angry. He rose way up out of the water three times trying to chase our boat! He was coming at us with such force that he created a wake of his own. Photo location: Selinda Reserve of northern Botswana. (Photo and caption by Curtis Simmons/National Geographic Photo Contest)