Two ancient bronze coins, which according to Israel Antiquities Authority archaeologists were struck by the Roman procurator of Judea, Valerius Gratus, in the year 17/18 CE and recently were revealed in excavations beneath the Western Wall in Jerusalem's Old City are exposed to the media' on November 23, 2011 in Israel. (Photo by Lior Mizrahi/Getty Images)

Camera trapper Xavier Hubert-Brierre put this large mirror on the side of a road through the jungle in Gabon and left a camera there to record how the animals would respond to their own reflections. A silverback gorilla thought it was seeing another silverback and responded by trying to scare off the potential challenger… (Photo by Xavier Hubert-Brierre/Johns Hopkins University Press)

The National September 11 Memorial & Museum (branded as 9/11 Memorial and 9/11 Memorial Museum) is the principal memorial and museum commemorating the September 11 attacks of 2001, which killed nearly 3,000 people, and the World Trade Center bombing of 1993, which killed six. The memorial is located at the World Trade Center site, on the former location of the Twin Towers, which were destroyed during the attacks. The World Trade Center Memorial Foundation was renamed the National September 11 Memorial & Museum at the World Trade Center in 2007.

A woman takes a selfie with “RoboThespian” at Robots, a major new exhibition at Science Museum in London, England on February 7, 2017. Exhibition showcases 500-year history of robots, with over 100 robots and the largest collection of humanoid robots ever displayed. (Photo by Tolga Akmen/Anadolu Agency/Getty Images)

A citizen rides in smog on December 20, 2016 in Jinan, Shandong Province of China. Air quality index (AQI) readings exceeded 400 and some schools have suspended classes in Jinan. (Photo by VCG/VCG via Getty Images)

These eye-catching photographs capture the special relationship between a group of farmers and elephants – with a gorgeous sunset in the background. Vithun Khamsong, a civil engineer, shot the images earlier this year while visiting Surin, Thailand. (Photo by Vithun Khamsong/Caters News Agency)

Jolon Clinton, 15, (L), and her sister, Halcy, 17, take photos of a fissure near their home on the outskirts of Pahoa during ongoing eruptions of the Kilauea Volcano in Hawaii, U.S., May 14, 2018. (Photo by Terray Sylvester/Reuters)

Models show creations by Chinese graduates from the China Academy of Art School of Design during the Show Town China Graduate Fashion Week in Beijing, China, 13 May 2018. (Photo by How Hwee Young/EPA/EFE)