Kids play in water to cool off during the scorching weather of a heatwave at a River Landing splash park in Saskatoon, Saskatchewan, Canada July 2, 2021. (Photo by David Stobbe/Reuters)

Passengers wearing protective masks travel on an over crowded train towards capital city, amid concerns about the spread of the coronavirus disease (COVID-19), in Colombo, Sri Lanka, July 8, 2020. (Photo by Dinuka Liyanawatte/Reuters)

A dog looks at a five-meter-long sperm whale stranded at San Bartolo beach, in Lima, on August 20, 2019. Surfers and policemen saved Tuesday an injured whale which remained stranded some hours at a beach in southern Lima, police informed. (Photo by Ernesto Benavides/AFP Photo)

In this September 27, 2017 file photo, girls walk past a wall riddled with bullet holes from shootings between rival drug traffickers, at the Rocinha slum, in Rio de Janeiro, Brazil. Violence is on the rise in Rio's slums after several years of decline, and the killings of kids have shocked even residents long inured to deaths from gangs and police. (Photo by Silvia Izquierdo/AP Photo)

Svetlana Tseyko feeds a 10-month-old moose named Grisha in the courtyard in the village of Abramy, some 160 km northwest of Minsk, on February 21, 2017. (Photo by Sergei Gapon/AFP Photo)

An Afghan girl harvests Cotton buds at a field on the outskirts of Balkh province, Afghanistan, November 15, 2014. (Photo by Sayed Mustafa/EPA)

In this Friday, February 1, 2019, photo, Filipino-Chinese display piggy banks at the start of celebrations leading to next week's Lunar New Year in Chinatown, Manila, Philippines. This year is the Year of the Earth Pig on the Lunar calendar and is supposed to represent abundance, diligence and generosity. (Photo by Bullit Marquez/AP Photo)

Macro or Micro? Scientists’ pictures baffle our sense of scale. It began when Stephen Young, a geography professor at Salem State University in Massachusetts, tricked his biologist colleague Paul Kelly into thinking a satellite image was one of his electron microscope scans. Can you guess whether they are close-up or very far away? (Photo by Paul Kelly)