First graders of a cadet's lyceum attend a ceremony to mark the start of the new school year in Kiev, Ukraine, September 1, 2015. September 1 marks the start of a new academic year for students in Ukraine.(Photo by Valentyn Ogirenko/Reuters)

1: Dubai's Burj Khalifa is the tallest building in the world, but perhaps not for long. Saudi Arabia has announced plans to build a 1 kilometer (3,280 foot) tower into the sky, to be named the Jeddah Tower, scheduled for completion in 2020. The Burj Khallifa currently stands at 2,716 ft. (Photo by Matthias Seifert/Reuters)

Opossums on their mothers back at a game reserve in Central Minnesota, USA, on September 2, 2013. (Photo by Caters News Agency)

A competitor participates in the Tough Mudder challenge near Henley-on-Thames in southern England May 2, 2015. (Photo by Eddie Keogh/Reuters)

People participate in a Zombie Walk in Sao Paulo, Brazil, November 2, 2016. (Photo by Nacho Doce/Reuters)

The Perseid Meteor Shower seen over The Scorhill Stone Circle in Dartmoor, Devon on August 2, 2016. (Photo by John Baker/SWNS.com)

A man sleeps at Beirut's Corniche, a seaside promenade, in Lebanon May 2, 2016. (Photo by Alia Haju/Reuters)

Guo Meiling of China jumps her Mini into the road during the 38th Dakar Rally in Arrecifes, Argentina, January 2, 2016. (Photo by Reuters/Stringer)