NASA captured stunning images of Mars’ winter wonderland. During the colder season, Mars’ landscape is completely transformed into quite literally an otherworldly and iridescent winter scene.

The Kashmir Valley is a large, bowl-like ravine that's around 84 miles (135 kilometers) long and 20 miles (32 km) wide. It is surrounded by mountains on all sides, including parts of the Himalayas ...

Photo: VCG/VCG via Getty Images The Perseid meteor shower over the natural reserve area of Wadi Al-Hitan (Valley of the Whales) at the desert of Al Fayoum Governorate, Egypt.

Now in its 15th year, this photo competition brings us the beauty of the avian world — while focusing on the tragic fact that two-thirds of North American birds are threatened by extinction.