A small section of the expanding remains of the Veil Nebula, a massive star that exploded about 8,000 years ago. The entire nebula is 110 light-years across, covering six full moons on the sky as seen from Earth, and resides about 2,100 light-years away in the constellation Cygnus, the Swan. Image taken by NASA's Hubble Space Telescope. Released September 24, 2015. (Photo by Reuters/NASA/ESA/Hubble Heritage Team)

A couple hugs while standing near a Christmas tree made out of plastic bins and plastic hampers outside the Museum of History in Monterrey, Mexico, December 4, 2015. The humble Christmas tree has a rich history, from evergreen trees used to symbolise eternal life in Ancient Egypt to tree worship among pagan Europeans. The modern version has its origins in Germany, where the song “O Tannenbaum” is still a festive favourite. Today the traditional tree with lights and decorations appears in cities including Washington, Moscow and Beirut. Alternative constructions range from recycled rubbish in Mexico City to old window frames in Rakvere, Estonia. Whatever the shape or size, the message is the same: Merry Christmas. (Photo by Neil Hall/Reuters)

“NASA's Mars rover Opportunity just celebrated its ninth anniversary on Mars – a mission that was originally meant to last just 90 days...” – The Atlantic. Photo: NASA's rover Opportunity visits Victoria Crater, viewed from orbit by the High Resolution Imaging Science Experiment on NASA's Mars Reconnaissance Orbiter in october of 2006. Opportunity is a small dot on the crater's lip, at top right. Opportunity first reached the crater's rim on September 27, 2006. (Photo by NASA/JPL-Caltech/University of Arizona via The Atlantic)

A female Marine prepares to throw a practice grenade during Marine Combat Training (MCT) on February 21, 2013 at Camp Lejeune, North Carolina. Since 1988 all non-infantry enlisted male Marines have been required to complete 29 days of basic combat skills training at MCT after graduating from boot camp. MCT has been required for all enlisted female Marines since 1997. About six percent of enlisted Marines are female. (Photo by Scott Olson)

Darlene Eddy packages up a chocolate Easter bunny that she made in her store Amazing Chocolates on March 28, 2013 in Hollywood, Florida. As Easter Sunday approaches chocolatiers are busy manufacturing many different types of delights for the holiday when Americans spend roughly $1.9 billion on Easter candy, second only to Halloween in candy consumption. Around ninety million chocolate Easter bunnies are produced each year, from white to dark chocolate, and with an unlimited varieties of styles. (Photo by Joe Raedle)

Yakutsk, a remote city in Eastern Siberia along the Lena River, is the coldest city in the world. Located 1840 km away from Irkoustk and 5000 km away from Moscow, this city founded in 1632 by the Cossacks imposes upon its inhabitants an extreme way of life. And yet, despite particularly harsh conditions, Yakutsk boasts a population of 270,000, or a quarter of the entire population of Siberia. No other place on the planet experiences the temperature extreme found here: in winter, the temperatures regularly fall to minus 40° (the coldest temperature recorded was –64°C) and in summer often reaches temperatures above 30°C. Photo: January 2013. A scene in Yakutsk, Siberia, the coldest city in the world. (Photo by Steeve Iuncker/Agence VU)

Dan McManus and his service dog Shadow hang glide together outside Salt Lake City, Utah, July 22, 2013. McManus suffers from anxiety and Shadow's presence and companionship help him to manage the symptoms. The two have been flying together for about nine years with a specially made harness for Shadow. (Photo by Jim Urquhart/Reuters)

Yves “Jetman”, Rossy made his first public performance in the United States on Tuesday during the afternoon air show at EAA AirVenture. As thousands of spectators leaned back and clicked cameras, Rossy jumped out of a helicopter with his 6-foot carbon fiber wing armed with four 45-pound-thrust JetCat engines strapped to his back. Photo: Jetman during a trial flight from Fond du Lac airport on Monday July 29, 2013. (Photo by Mike Shore/Courtesy of Breitling)