Mr. Zhong Hua, of Johns Hopkins University School of Medicine, took this image of the peripheral nerves (those outside of the brain) in an 11.5-day-old mouse embryo, magnified five times. (Photo by Zhong Hua)

Lightning strikes the Willis Tower (formerly Sears Tower) in downtown on June 12, 2013 in Chicago, Illinois. (Photo by Scott Olson/Getty Images)

Photo taken on September 19, 2015 shows a baby Brazilian opossum at the “Parque Estoril” zoo in Sao Bernardo do Campo of Sao Paulo, Brazil. According to local press, the “Parque Estoril” zoo houses currently 23 orphan cubs of wild animals rescued in the south region of Sao Paulo, victims of illegal wildlife trade or problems caused by urban growth. According to the zoo, all the animals arrived in the last three months, and many of them, not being able to be reintroduced to their natural habitat, will be used as examples in environmental education classes. (Photo by Rahel Patrasso/Xinhua via ZUMA Wire)

“A Mothers Tail”. A baby cub pulls on his mother's tail to get attention. Photo location: Masai Mara, Kenya. (Photo and caption by Tori Marsh/National Geographic Photo Contest)

Cars float up from a car garage in a mixture of storm water and gasoline in lower Manhattan as workers begin the process of pumping out the mess. (Photo by Carolyn Cole/Los Angeles Times/MCT)

An officer of the Afghan border police throws an assault rifle to a policeman participating in a military exercise on the outskirts of Herat, Afghanistan, Monday, September 7, 2015. Twelve female and seventy male border police personnel participated in the military exercise near the border with Iran in Herat province. (Photo by Hoshang Hashimi/AP Photo)

Two young boys kneel on stools on either side of a round table as one uses a match to this the other's cigarette, November 12, 1928. (Photo by FPG/Getty Images)

The villas of Marabe Al Dhafra in Abu Dhabi, United Arab Emirates are home to approximately 2,000 people. Located in one of the hottest regions of the world, the record high temperature here is 49.2C° (120.6F°). (Photo by Benjamin Grant/Penguin Random House)