People walk on the Patriarch's bridge decorated for Christmas and New Year celebrations with the Christ the Savior Cathedral in the background in Moscow, Russia, Monday, December 16, 2019. (Photo by Alexander Zemlianichenko/AP Photo)

Ukrainians wearing traditional costumes sing Kolyadky or Ukrainian Christmas Carols, as a part of Orthodox Christmas in Kiev, Ukraine, Thursday, January 7 2016. Orthodox Christians mark their traditional Christmas Day Jan. 7, with many ancient symbolic events. (Photo by Sergei Chuzavkov/AP Photo)

Claudionor Jose de Deus, wearing a Santa Claus costume, arrives at Santa Rosa community to distribute presents to children, on the shores of the Amazon River in rural Manaus, Brazil, December 19, 2015. Jose de Deus is part of a volunteer group that distributes toys to children from poor neighborhoods and riverside communities that are distant from the city. (Photo by Bruno Kelly/Reuters)

Passengers travel on the London train and underground system during the Christmas party season, December 18, 2015. (Photo by Paul Hackett/Reuters)

Brain-on-a-chip. Dazzling in green and magenta this image shows the nerve fibres (in green) produced by neural stem cells (in magenta) as they grow on a synthetic gel. Captured by a technique known as confocal microscopy, the image is part of research shedding light on how tinkering with the environment can affect the way in which nerve fibres grow. (Photo by Collin Edington and Iris Lee/Massachusetts Institute of Technology/Wellcome Images)

The tempestuous stellar nursery called the Carina Nebula, located 7,500 light-years away from Earth in the southern constellation Carina. (Photo by Reuters/NASA)

An elephant dressed in a Santa Claus costume gives out gifts to students to mark the Christmas season at a school in Ayutthaya province on December 24, 2010. The event was held as part of a campaign to promote Christmas in Thailand. (Photo by Pornchai Kittiwongsakul/AFP Photo)