A woman smokes marijuana during the annual 4/20 marijuana rally on Parliament Hill in Ottawa, Ontario, Canada, April 20, 2017. (Photo by Chris Wattie/Reuters)

A robot is seen on Mount Etna, Italy on July 4, 2017. Mount Etna, in Sicily, is a test bed for the approximately three-foot high, four-wheeled machine ahead of a future mission to the moon. It is being conducted by the German Aerospace Centre, the agency which runs Germany's space programme. (Photo by Antonio Parrinello/Reuters)

Aerobatic pilot Sean D. Tucker flies in the two-seat Oracle Extra airplane over downtown Chicago skyline, Wednesday, June 8, 2016. Tucker will perform before the start of of the America's Cup World Series racing on Saturday and Sunday. (Photo by Kiichiro Sato/AP Photo)

“Light From Heaven”. Taken around Mount Bromo, East Java, Indonesia in the morning. Photo location: East Java, Indonesia. (Photo and caption by Pimpin Nagawan/National Geographic Photo Contest)

ATTENTION! All pictures are presented in high resolution. To see Hi-Res images – just TWICE click on any picture. In other words, click small picture – opens the BIG picture. Click BIG picture – opens VERY BIG picture.

In this June 1, 2016 photo, Maria Arias stands near her kitchen as she puts on earrings while getting ready for school in Caracas, Venezuela. So many students have fainted from hunger at Maria's school that administrators told parents to keep their children home until they could find more food. (Photo by Ariana Cubillos/AP Photo)

Israeli soldiers cry during a state memorial ceremony marking two years since the 2014 Gaza war “Operation Protective Edge” at Mount Herzl military cemetery in in Jerusalem, Israel, 26 July 2016. More than 2.000 people were killed in the conflicts between Israel and Palestine. (Photo by Abir Sultan/EPA)

NASA's DHC-3 Otter plane flies in Operation IceBridge-Alaska surveys of mountain glaciers in Alaska in this image released on September 18, 2014. Over the past few decades, average global temperatures have been on the rise, and this warming is happening two to three times faster in the Arctic. (Photo by Chris Larsen/Reuters/NASA/University of Alaska-Fairbanks)

A security man keeps guard during Malawi's President elect Arthur Peter Mutharika swearing in ceremony at Kamuzu Stadium in Blantyre on May 28, 2019, after a contentious election marred by allegations of fraud and vote-rigging. The Malawi Electoral Commission announced on Monday that Mutharika, who heads the ruling Democratic Progressive Party (DPP), had narrowly won last week's vote after an injunction barring the release of the results was lifted. (Photo by Amos Gumulira/AFP Photo)