A group of friends take selfies in a lit sphere at the Lincoln Park Zoo's Zoolights in Chicago, the United States, on Dec. 16, 2019. Zoolights is an annual event to greet Christmas and the New Year. (Photo by Joel Lerner/Xinhua)

An installation depicting a penguin sliding down an igloo is on display at the Lincoln Park Zoo's Zoolights in Chicago, the United States, on Dec. 16, 2019. Zoolights is an annual event to greet Christmas and the New Year. (Photo by Joel Lerner/Xinhua)

An installation depicting a pair of penguins is on display at the Lincoln Park Zoo's Zoolights in Chicago, the United States, on Dec. 16, 2019. Zoolights is an annual event to greet Christmas and the New Year. (Photo by Joel Lerner/Xinhua)

An installation depicting a lion and a lioness is on display at the Lincoln Park Zoo's Zoolights in Chicago, the United States, on Dec. 16, 2019. Zoolights is an annual event to greet Christmas and the New Year. (Photo by Joel Lerner/Xinhua)

An installation representing a pair of rainbow zebras is seen at the Lincoln Park Zoo's Zoolights in Chicago, the United States, on Dec. 16, 2019. Zoolights is an annual event to greet Christmas and the New Year. (Photo by Joel Lerner/Xinhua)

Light installations are seen at the Lincoln Park Zoo's Zoolights in Chicago, the United States, on Dec. 16, 2019. Zoolights is an annual event to greet Christmas and the New Year. (Photo by Joel Lerner/Xinhua)

People visit the Lincoln Park Zoo's Zoolights in Chicago, the United States, on Dec. 16, 2019. Zoolights is an annual event to greet Christmas and the New Year. (Photo by Joel Lerner/Xinhua)

People visit the Lincoln Park Zoo's Zoolights in Chicago, the United States, on Dec. 16, 2019. Zoolights is an annual event to greet Christmas and the New Year. (Photo by Joel Lerner/Xinhua)

People visit the Lincoln Park Zoo's Zoolights in Chicago, the United States, on Dec. 16, 2019. Zoolights is an annual event to greet Christmas and the New Year. (Photo by Joel Lerner/Xinhua)

People visit the Lincoln Park Zoo's Zoolights in Chicago, the United States, on Dec. 16, 2019. Zoolights is an annual event to greet Christmas and the New Year. (Photo by Joel Lerner/Xinhua)

People visit the Lincoln Park Zoo's Zoolights in Chicago, the United States, on Dec. 16, 2019. Zoolights is an annual event to greet Christmas and the New Year. (Photo by Joel Lerner/Xinhua)

People visit the Lincoln Park Zoo's Zoolights in Chicago, the United States, on Dec. 16, 2019. Zoolights is an annual event to greet Christmas and the New Year. (Photo by Joel Lerner/Xinhua)