On the final leg of a six-week United States of America road trip, I was driving east across Interstate 40 when a spot storm with golf ball-sized hail struck. A sign near Groom, Texas, announcing the "largest cross in the western hemisphere" explained the large crucifix I’d been wondering about for miles on the highway; it seemed like an OK place to wait out the storm. On my way to getting stuck in the mud and a giant double rainbow, I saw this silhouetted view of the cross, splitting the sunny sky from the stormy plains. (Photo and caption by Brad Maule) #

This picture was taken during the Rinjani volcano trek on Lombok Island in Indonesia at sunrise. (Photo and caption by David Bismuth) #

An example of photo luminescence in coral in West Papua (Photo and caption by Stephen Martin) #

A male gelada baboon on the Guassa Plateau of the Ethiopian Highlands enjoys a good grooming. (Photo and caption by Robin Moore) #

I was in the front car of the short subway between Pudong and the Bund, and was treated to the wonderful spectacle of an oncoming train in the tunnel's changing light show. I put my camera up to the window and shot as fast as possible to get this image. (Photo and caption by Gail von Bergen Ryan) #

A stone's-eye-view of two tracks made by the sailing stones of Death Valley's Racetrack playa. The dried clay surface has a beautiful texture, and there is a palpable aura of mystery over the entire three-square-mile playa. The Racetrack was not entirely free of human influence though: several weeks before this taken many of the stones were stolen, leaving long trails without a traveler at the end. (Photo and caption by Tucker Sylvestro) #

On my second day visiting the astounding Iguazu falls on the Brazilian side I was forced to change to my telephoto lens as my wide angle had been damaged by the water vapour. In had rained solid for 10 days prior to my arrival and so the falls were at their most spectacular. Standing on the elevated viewing platform I was able to shoot this school group who stood transfixed, emphasizing the incredible size of the falls. (Photo and caption by Ian Kelsall) #

I took this picture on a sunny fall afternoon on a prairie near Chicago, Illinois. To improve the color saturation, I blocked the sunlight with my body. The blue background came straight from the camera. The image was not altered with any editor. (Photo and caption by Richard Susanto) #

My grandfather was born and raised on our New Zealand farm. He and my grandmother were married nearly 60 years. Preparing for a photo in the barley, my grandmother lovingly reached up to adjust his hat. This was his last harvest. (Photo and caption by Gemma Collier) #

During a rainy, cloudy morning at the Wild Goose scenic overlook on St. Mary Lake in Glacier National Park, Montana, the sun peeped from under the cloud cover long enough to paint a golden-yellow swath across the face of the mountain for maybe 15 minutes before disappearing again. (Photo and caption by Rebecca Latson) #

A young orangutan swings from tree to tree in Tanjung Puting National Park in Indonesian Borneo. (Photo and caption by Sean Crane) #

This is about one hour of firefly activity near my home in rural Ontario. The precision of the background star trails is an interesting contrast to the chaotic pattern of the firefly flashes. (Photo and caption by Steve Irvine) #

The edge of an iceberg floating just off the coast of Antarctica. (Photo and caption by Mike Matas) #

While visiting Kruger National Park with my son, we came across two male hippos battling for dominance as we crossed a bridge over the Sabie River. The bellowing from the animals as they fought their bloody battle was incredible. They first fought in the shallows near the bank and then moved into the deeper part of the river. We don't know how it turned out but we were so glad to see the spectacle. (Photo and caption by Steve Mandel) #

Andrew and his friend, a young sperm whale named Scar, were swimming together off the west coast of Dominica. The two of them became "friends" after Andrew saved Scar's life. (Photo and caption by Peter Allinson) #

The Darvaza natural gas crater is located in the center of the Karakum Desert in the central Asian country of Turkmenistan. The crater resulted after a Soviet natural gas exploration accident in the 1950s and has been burning ever since. The crater is approximately 60 meters in diameter and its depth is approximately 20 meters. (Photo and caption by Natalja Silver) #

When the wave conditions are right a wave appears, infrequently, as a result of the splash back off the cliff connecting with an incoming wave. This causes the incoming wave to pop up, creating fan-like shapes. On this particular day, over the two hours I spent on the rocks, this wave only appeared once. This is that shot. (Photo and caption by Aaron Feinberg) #

David Hanson crosses a fallen log beneath soaring trees and a lingering fog in Washington's Olympic National Park. (Photo and caption by Michael Hanson) #

Even during the Arirang Mass Games in North Korea, the ultimate expression of the state ideology, an individual can still sometimes stand out from the crowd and break free of the collective. If only just for a moment. (Photo and caption by Brendyn Zachary) #

Cary stands on a deserted road in Central Ohio, at sunset. (Photo and caption by Lisa Roberts) #

This bee was unfortunate enough to land in my pool, but he made some amazing patterns buzzing around in the water. He later escaped. (Photo and caption by Michael Johnson) #

Taken at Kwena Croc Farm in South Africa (Photo and caption by Wayne Holloway) #

This is one view of many dunes found in Jordan. Two steps forward and one step back made for a challenging ascent. (Photo and caption by Andrew Cwiklewich) #

Curious gulls on Sanibel Island, Florida. Meet my friend, "Gull-i-Bel"!!! (Photo and caption by Richard Rush)