'Step on Board,' the Harriet Tubman Memorial, sculpted by Fern Cunningham, in Boston, Massachusetts (© Anthony Pleva/Alamy)

A section of a large mosaic of Ida B. Wells displayed at Union Station in Washington, DC, in August 2020 (© Manuel Balce Ceneta/AP Photo)

Volcano Llaima with Araucaria trees in the foreground, Conguillío National Park, Chile (© Fotografías Jorge León Cabello/Getty Images)

Female lions in the forest surrounding Lake Nakuru, Kenya (© Scott Davis/Tandem Stills + Motion)

Nusa Dua coast with breakwater, Bali, Indonesia (© Dkart/Getty Images)

Mineral-laden water in the Rio Tinto, Minas de Riotinto mining area, Huelva province, Andalusia, Spain (© David Santiago Garcia/Getty Images)

Komodo National Park, Indonesia (© Thrithot/Adobe Stock)

Great blue herons in the Wakodahatchee Wetlands, Delray Beach, Florida (© Marie Hickman/Getty Images)

View of the Notorious RBG mural by the street artist Elle in New York City (© lev radin/Alamy)

Foothills of the Diablo Range in the East Bay region of Northern California (© Jeff Lewis/Tandem Stills + Motion)

Thor's Well at Cape Perpetua on the Oregon coast (© Cavan Images/Offset by Shutterstock)

A balloon flies over the Pyramid of the Sun at sunrise in Teotihuacan, Mexico (© Marco Ugarte/AP Photo)

Common rhododendrons in Semper Forest Park, Rügen, Germany (© Sandra Bartocha/Minden Pictures)

Astronomical clock, Lyon, France (© kyolshin/Alamy)

Screech owl resting in a tree cavity, Massapequa Preserve, Long Island, New York (© Vicki Jauron, Babylon and Beyond Photography/Getty Images)

Giant panda cub at Bifengxia Panda Base, Sichuan, China (© Suzi Eszterhas/Minden Pictures)

Inisheer, the smallest of the three Aran Islands, in Galway Bay, Ireland (© Chris Hill/Minden Pictures)

Mount Etna erupting in 2013, Sicily, Italy (© Wead/Alamy Live News)

Aerial view of the City of Adelaide shipwreck with trees growing on it, Magnetic Island, Queensland, Australia (© Amazing Aerial Agency/Offset by Shutterstock)

Sundial on Parnidis Dune, Curonian Spit, Lithuania (© amoklv/Getty Images)

Bluebell flowers carpet the Hallerbos forest floor, Flanders, Belgium (© Jason Langley/plainpicture)

Tuskegee Airmen reading a map (© Bettmann/Getty Images)

Satellite image of the Mania River in Madagascar (© NASA Earth Observatory image by Joshua Stevens, using Landsat data from the US Geological Survey)

Humpback whale mother pushes her sleeping calf to the surface, Maui, Hawaii (© Ralph Pace/Minden Pictures)

Ancient Roman gold mining site of Las Médulas, León province, Spain (© David Santiago Garcia/Getty Images)

Cradle Mountain-Lake St. Clair National Park, Tasmania, Australia (© Paparwin Tanupatarachai/Getty Images)

Mountain hare running across snow-covered upland, Scotland (© SCOTLAND: The Big Picture/Minden Pictures)

The Jefferson Memorial during the National Cherry Blossom Festival in Washington, DC (© Rae Gabrielle/Alamy)

Reynisdrangar (basalt rock formations) on Reynisfjara Beach, Iceland (© Cavan Images/Getty Images)

Detail of an ostrich fern in spring, Washington state (© Stephen Matera/Tandem Stills + Motion)

Raja Ampat, an archipelago in Indonesia (© Amazing Aerial Agency/Offset by Shutterstock)