Lindsay Knutson plays in the heavy snow with her family dog, Aspen, and daughter Flora Bejblik, 4, cq, as her husband Bob Bejblik, rear left, shovels, Tuesday, March 5, 2013 in southwest Minneapolis. The National Weather Service predicted a two-day snow total of 8 to 12 inches for much of southeastern and east-central Minnesota, including the Twin Cities. (Photo by Elizabeth Flores/AP Photo/The Star Tribune)

An aerial view shows the 11/19 pit and twin slag heaps at the former coal mine site in Loos-en-Gohelle, northern France, November 1, 2015. Loos-en-Gohelle, a town of 7000 inhabitants in the North of France, marked by the closure of coal mines in 1970, has demonstrated a successful transition from coal to a green economy. (Photo by Pascal Rossignol/Reuters)

Tourists kissing front of Malaysia's landmark Petronas Twin Towers with lights on before turned off to mark Earth Hour 2016 in Kuala Lumpur, Malaysia, 19 March 2016. Earth Hour takes place worldwide at 8.30 p.m. local time and is a global call to turn off lights for 60 minutes to raise awareness of the danger of global climatic change (Photo by Fazry Ismail/EPA)

The twin lighthouses of St Joseph on Lake Michigan have been transformed by a winter storm. Ice encases the buildings, giant icicles hang from the piers and the beach is frosted white. Here: Huge icicles hang from the pier. (Photo by Mike Kline/Barcroft Media)

“The Lockheed Martin X-33 is an unmanned, sub-scale technology demonstrator suborbital spaceplane developed in the 1990s under the U.S. government-funded Space Launch Initiative program”. – Wikipedia

Photo: An Artist's Rendering Shows How Nasa's X-33 Technology Demonstrator, A Cost-Cutting Fully Reusable Single-Stage-To-Orbit Space Vehicle, Will Look Upon Completion. The 67 Foot-Long, 278,600 Pound, Twin Engine Space Vehicle, Capable Of Reaching Speeds In Excess Of Mach 15, Will Lead To The Construction Of A 127 Foot-Long, 2,186,000 Pound Version With Seven Engines And A 50,000 Pound Payload Capacity Called The “Venturestar”. (Photo By Nasa/Getty Images)

The National September 11 Memorial & Museum (branded as 9/11 Memorial and 9/11 Memorial Museum) is the principal memorial and museum commemorating the September 11 attacks of 2001, which killed nearly 3,000 people, and the World Trade Center bombing of 1993, which killed six. The memorial is located at the World Trade Center site, on the former location of the Twin Towers, which were destroyed during the attacks. The World Trade Center Memorial Foundation was renamed the National September 11 Memorial & Museum at the World Trade Center in 2007.

Omar Gamal, a 28-year-old pigeon keeper, stands next to his pigeon coop on his rooftop in the Egyptian capital's twin city of Giza on February 21, 2021, with the Pyramids of (R to L) Khufu (Cheops), Khafre (Chephren), and Menkaure (Menkheres) in the background. An ancient tradition handed down through the generations, the practice of domesticating pigeons stretches across borders from the banks of the Nile to north Africa and beyond, with people not only training birds for competitions, but also serving them up as a dining delicacy. (Photo by Khaled Desouki/AFP Photo)

Sunset is seen through smoke from the Wallow fire June 8, 2011 in Springerville, Arizona. Hundreds of thousands of acres have burned in eastern Arizona prompting evacuations by residents. Smoke loomed over the twin towns of Eager and Springerville, home to about 7,000 people north of the fire. (Photo by Eric Thayer/Getty Images)