Humpback whale mother pushes her sleeping calf to the surface, Maui, Hawaii

Satellite image of the Mania River in Madagascar

Tuskegee Airmen reading a map

Bluebell flowers carpet the Hallerbos forest floor, Flanders, Belgium

Sundial on Parnidis Dune, Curonian Spit, Lithuania

Aerial view of the City of Adelaide shipwreck with trees growing on it, Magnetic Island, Queensland, Australia

Mount Etna erupting in 2013, Sicily, Italy

Inisheer, the smallest of the three Aran Islands, in Galway Bay, Ireland

Giant panda cub at Bifengxia Panda Base, Sichuan, China

Screech owl resting in a tree cavity, Massapequa Preserve, Long Island, New York

Astronomical clock, Lyon, France

Common rhododendrons in Semper Forest Park, Rügen, Germany

A balloon flies over the Pyramid of the Sun at sunrise in Teotihuacan, Mexico

Thor's Well at Cape Perpetua on the Oregon coast

'Step on Board,' the Harriet Tubman Memorial, sculpted by Fern Cunningham, in Boston, Massachusetts

Foothills of the Diablo Range in the East Bay region of Northern California

View of the Notorious RBG mural by the street artist Elle in New York City

Great blue herons in the Wakodahatchee Wetlands, Delray Beach, Florida

Komodo National Park, Indonesia

Mineral-laden water in the Rio Tinto, Minas de Riotinto mining area, Huelva province, Andalusia, Spain