The Northern Lights glow green in a spectacular light show above a field of trees frozen solid with snow. (Photo by Jaak Sarv/Solent News & Photo Agency)

Revellers parade for Gavioes da Fiel samba school during carnival in Sao Paulo, Brazil, February 6, 2016. (Photo by Paulo Whitaker/Reuters)

An instructor (C) adjusts the posture of students of flight attendant major during a training session at Anhui Foreign Languages University, in Hefei, Anhui province, China, May 25, 2015. (Photo by Reuters/China Daily)

With less than a week before Election Day, a Halloween skeleton holds a vote sign outside a home in Falls Church, Virginia, October 29, 2020. (Photo by Kevin Lamarque/Reuters)

Rajesh Babu, a police officer, wearing a helmet depicting coronavirus, requests a commuter to stay at home during a 21-day nationwide lockdown to limit the spreading of coronavirus disease (COVID-19), in Chennai, India, March 28, 2020. (Photo by P. Ravikumar/Reuters)

Vehicles move past a man wearing a protective mask against COVID-19 as he waits for the bus in Karachi, Pakistan on December 11, 2020. (Photo by Akhtar Soomro/Reuters)

People wearing face masks to help curb the spread of the coronavirus enjoy a social dance at a public park in Beijing, Tuesday, January 12, 2021. Lockdowns have been expanded and a major political conference postponed in a province next to Beijing that is the scene of China's most serious recent COVID-19 outbreak. (Photo by Andy Wong/AP Photo)

A man photographs “Mount Recyclemore”, an artwork depicting the G7 leaders looking towards Carbis Bay, made from electronic waste by Joe Rush and Alex Wreckage, ahead of the G7 summit, at Hayle Towans in Cornwall, Britain, June 8, 2021. (Photo by Tom Nicholson/Reuters)