Ammunition airlift into besieged Khe Sanh, Operation Pegasus, April 1968. (Photo by Larry Burrows/AP Photo)

A Flame Skimmer or Firecracker Skimmer dragonfly (Libellula saturata) rests on a small branch in Topanga, California, USA, 18 June 2018. The Flame Skimmer dragonfly is found in the Western United States near ponds and creeks. (Photo by Mike Nelson/EPA/EFE)

Two brown bears bathe in their enclosure at the Wildpark Poing in Poing, Germany, Wednesday, August 8, 2018. (Photo by Lino Mirgeler/Deutsche Presse-Agentur via AP Photo)

People dance during a heavy metal concert at Omni Space in Beijing, China, August 14, 2020. China boasts a small but buoyant heavy metal scene, where bands mix genre standards with Chinese elements. Black metal is a sub-genre that creates a dark, moody atmosphere layering heavily distorted guitars and high-pitched vocals. (Photo by Thomas Peter/Reuters)

Students wearing masks rest amid the coronavirus disease (COVID-19) pandemic in Seoul, South Korea, August 25, 2020. (Photo by Kim Hong-Ji/Reuters)

A handout TV grab made available by the Demiroren News Agency (DHA) on September 12, 2020, shows a freak sandstorm sweeping over Polatli, in Ankara, on September 12, 2020. A freak sandstorm hit Ankara on September 12, 2020, the Turkish capital's mayor said, as officials said six people were injured after strong winds. (Photo by Handout/DHA via AFP Photo)

In this undated photo, the aerial view of Jingxing Bridge in autumn is shown, with trees turning red around and the West Lake going under it, in Hangzhou city, east China's Zhejiang province on November 18, 2020. (Photo by Rex Features/Shutterstock)

A civil defence volunteer wearing a Covid-19 coronavirus-themed helmet holds a placard as he takes part in an awareness campaign at a market in New Delhi on November 25, 2020. (Photo by Sajjad Hussain/AFP Photo)