A demonstrator shows her arm with the name “Marielle” written on it, as she performs during a protest against the murder of councilwoman Marielle Franco in Rio de Janeiro, Brazil, Tuesday, March 20, 2018. Franco's murder came just a month after the government put the military in charge of security in Rio, which is experiencing a sharp spike in violence less than two years after hosting the 2016 Summer Olympics. (Photo by Leo Correa/AP Photo)

A couple watches the sunset over a sea of fog covering the Geneva Lake from Chardonne, Switzerland, 28 December 2015. (Photo by Jean-Christophe Bott/EPA)

Mini-pigs perform during the presentation in Balashikha, Russia on December 19, 2018. (Photo by Maxim Shemetov/Reuters)

A herd of wildebeest cross the skyline against the fading light in Masai Mara, Kenya, 25 August 2017. Stunning sunset photos silhouette Africa’s wildlife against streaks of orange and red sky. In August, German photographer Ingo Gerlach was on safari in the Masai Mara when he convinced his safari guide to stop and take in the sunset. The wildlife photographer was rewarded with his patience by an eye-catching sunset, which cast Africa’s wildlife into dark shadows against the vibrant skies. (Photo by Ingo Gerlach/Barcroft Images)

A Chinese tourist uses the scarf of a friend as she is helped while she and others struggle to climb in the wind on an icy section of the Great Wall at Badaling, on a cold day after a snowfall on November 30, 2019 in Beijing, China. (Photo by Kevin Frayer/Getty Images)

A Ukrainian serviceman fires a 2S7 Pion self-propelled gun during military exercises near the village of Divychky in Kiev region, Ukraine, October 21, 2016. (Photo by Valentyn Ogirenko/Reuters)

In this artist's impression supplied by the ESO (European Southern Observatory) on April 25, 2007, the planetary system around the red dwarf, Gliese 581, is pictured showing what astronomers believe is the most earth like planet found outside our solar system to date. Using the ESO 3.6-m telescope in Chile, astronomers have uncovered the planet which could have water running on its surface. The planet orbits the faint star Gliese 581, which is 20.5 light-years away in the constellation Libra. (Photo by ESO via Getty Images)

People decorate a street with candles inside oranges during the Epitaph ceremony during Good Friday's “Apokathelosis”, the Descent of Christ's dead body from the Cross, which forms a key part of Orthodox Easter, in the southern city of Leonidio, at the Peloponnese peninsula on April 26, 2019. Millions of Greeks flock to churches around the country this week to celebrate Easter, the country's foremost religious celebration. (Photo by Aris Messinis/AFP Photo)