This image is NGC 6543 known as the Cat's Eye Nebula as it appears to the Chandra X-Ray Observatory and Hubble Telescope. A planetary nebula is a phase of stellar evolution that the sun should experience several billion years from now, when it expands to become a red giant and then sheds most of its outer layers, leaving behind a hot core that contracts to form a dense white dwarf star. This image was released October 10, 2012. (Photo by J. Kastner/NASA/CXC/RIT)

Homeless people queue to get free hot food organized by social services during frost winter day in-Kiev on December 18, 2012. Nineteen people died of exposure in Ukraine in the last 24 hours amid temperatures of minus 20 degrees Celsius (minus 4 degrees Fahrenheit), bringing the toll this month to 37, the health ministry said Tuesday. (Photo by Sergei Supinsky/AFP Photo)

A person dressed as the Statue of Liberty pays for a hot dog on a side street near the 51st Annual Village Halloween Parade in New York, New York, USA, 31 October 2024. The annual holiday parade passes through the city's Greenwich Village neighborhood and claims to be the largest Halloween parade in the world. (Photo by Justin Lane/EPA/EFE)

“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)

Northeastern girls getting commando training at the Delhi Police Training Centre, Jharoda Kalan on September 4, 2017 in New Delhi, India. For the first time ever, Delhi Police are providing commando training to 40 young women from the Northeast. Once the commando training is over, these girls will be a part of the «Parakram Vans», an initiative taken by Delhi Police against terrorism. (Photo by Manoj Verma/Hindustan Times via Getty Images)

A girl takes pictures after opening ceremony at Shanghai Disney Resort in Shanghai, China, June 16, 2016. (Photo by Aly Song/Reuters)

A Bangladeshi girl plays on a swing, in Dhaka, Bangladesh, December 27, 2016. (Photo by Mohammad Ponir Hossain/Reuters)

Two girls in cosplay dresses walk in the street in Beijing on March 27, 2017. (Photo by Fred Dufour/AFP Photo)