Photographer and animal lover Chris Keeney shows how to use a PetCam with your own pet and offers expert technical know-how and inspiring creative suggestions to get you started. This is Coulee, a border collie/golden retriver mix from Lethbridge, Alberta, Canada. (Photo by Chris Keeney/Princeton Architectural Press)

A coil-shaped Helix Nebula showing a fine web of filamentary “bicycle-spoke” features embedded in the colorful red and blue ring of gas. At 650 light-years away, the Helix is one of the nearest planetary nebulae to Earth. A planetary nebula is the glowing gas around a dying, Sun-like star. (Photo by Reuters/NASA)

Ludivine Sagna walks the runway and wears a chocolate costume made by designer and a chocolate maker during the Fashion Chocolate show at Salon du Chocolat at Parc des Expositions Porte de Versailles in Paris, France, October 28, 2014. (Photo by LAURENTVU/SIPA Press)

These rare photos capture the Flight Deck (cockpit) of the Space Shuttle Endeavour, fully powered for one of the final times. Just a few weeks later, at 9:58am EDT on May 11, Endeavour was powered down for the final time in history. It was the last of the three space shuttles to have power. Below, other views show the mid-deck, gutted of its lockers and storage areas, and three final photos show the white room entrance in the Orbiter Processing Facility, signed by thousands over the years.

This combination of April 15, 2013 and April 2, 2014 photos show a police officer clearing Boylston Street following a bomb blast near the finish line of the 2013 Boston Marathon, and pedestrians crossing at the same corner nearly a year later in Boston. (Photo by Charles Krupa/AP Photo)

A model has makeup applied backstage prior to Lebanese designer Zuhair Murad fashion show held during the Haute Couture Fall/Winter 2014-2015 fashion collections in Paris July 10, 2014. (Photo by Philippe Wojazer/Reuters)

David Bowie, 1974. David Bowie's quirky character and style was perfectly encapsulated in this shot by Terry O'Neill, which shows the music legend posing next to a barking dog on the artwork for his 1974 album “Diamond Dogs” in London. (Photo by Terry O'Neill)

Holly Spring, a New Zealand photographer, says she is inspired by her daughter Violet, who was born with multiple ailments; Hirschsprung’s Disease, a blockage of the large intestine and Symbrachydactyly, a limb abnormality. The series was designed to show her daughter that she “can live a life without obstacles”. (Photo by Holly Spring)