Demonstrators run inside of subway after clashing with riot police during a protest to denounce the housing crisis and evictions, in Barcelona, Spain, on September 25, 2024. (Photo by Nacho Doce/Reuters)

British-Albanian singer Dua Lipa performs during 2024 Austin City Limits Music Festival at Zilker Park on October 05, 2024 in Austin, Texas. (Photo by Erika Goldring/WireImage)

Tourists wearing hats pose for a photo next to a Christmas tree on Christmas Day at Bondi Beach in Sydney on December 25, 2024. (Photo by David Gray/AFP Photo)

“A small British company with a dream of building a re-usable space plane has won an important endorsement from the European Space Agency (ESA) after completing key tests on its novel engine technology. Reaction Engines Ltd believes its Sabre engine, which would operate like a jet engine in the atmosphere and a rocket in space, could displace rockets for space access and transform air travel by bringing any destination on Earth to no more than four hours away”. – Chris Wickham via Reuters. Photo: Artist's impression of Skylon. (Photo by Reaction Engines Ltd)

“Contrails (short for “condensation trails”) or vapour trails are artificial clouds that are the visible trails of condensed water vapour made by the exhaust of aircraft engines. As the hot exhaust gases cool in the surrounding air they may precipitate a cloud of microscopic water droplets or, if the air is cold enough, tiny ice crystals”. – Wikipedia

Photo: An airplane leaves a vapor trail as it flies in front of he moon on January 17, 2007 above Hanover, Germany. (Photo by Alexander Hassenstein/Getty Images)

Mary McHugh mourns her slain fiance Sgt. James Regan at “Section 60” of the Arlington National Cemetery May 27, 2007. Regan, a US Army Ranger, was killed by an IED explosion in Iraq. (Photo by John Moore/Getty Images)

A singer drinks from a huge bowl of beer on-stage as he pays tribute to the customers after performing at an entertainment club in Beijing, on May 8, 2014. (Photo by Jason Lee/Reuters)

A South Sudanese model applies make-up during the Festival of Fashion and Arts for Peace in Juba August 9, 2014. (Photo by Andreea Campeanu/Reuters)