A Geminid meteor streaks diagonally across the sky against a field of star trails behind one of the peaks of the Seven Sisters rock formation in this long exposure early December 14, 2007 in the Valley of Fire State Park in Nevada. The meteor display, known as the Geminid meteor shower because it appears to radiate from near the star Castor in the constellation Gemini, is thought to be the result of debris cast off from an asteroid-like object called 3200 Phaethon. The shower is visible every December. (Photo by Ethan Miller/Getty Images)

A Tibetan girl reacts as she gets ready to perform in a function organised to mark “Losar” or the Tibetan New Year in Kathmandu, Nepal, February 11, 2016. (Photo by Navesh Chitrakar/Reuters)

In this Thursday, February 9, 2017 photo, a Bangladeshi boy pulls a rickshaw loaded with strips of leather at the highly polluted Hazaribagh tannery area in Dhaka, Bangladesh. Hazardous, heavily polluting tanneries with workers as young as 14 supplied leather to companies that make shoes and handbags for Western brands, a nonprofit group that investigates supply chains says. (Photo by A.M. Ahad/AP Photo)

LONDON - JUNE 04: A piece entitled “Entrance into wood” by Elke Krystufek goes on show at The Royal Academy Summer Exhibition on June 4, 2008 in London. In it's 240th year, the exhibition displays a wide range of recent work by both established and emerging artists. 10,000 artists submitted work for selection this year. (Photo by Peter Macdiarmid/Getty Images)

“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)

A man dressed in traditional clothes tries to pull his opponent over the table at the 40th Alpine Country Championships in Fingerhakeln_finger wrestling_ in Woernsmuehl, Germany, Thursday, May 25, 2017. Competitors battled for the title in this traditional rural sport where the winner has to pull his opponent over a marked line on the table. (Photo by Matthias Schrader/AP Photo)

Taking the highways in North Korea is a great experience as it allows to see the daily life of the country not controled by the government like in Pyongyang. They connect the main towns of the countries and are totally empty of cars. Here: The kind of scene you can see along the highway. Overloaded trucks but broken down with lot of smoke coming out... I was allowed to make those pics as after lunch, my guides were enjoying the confort of the bus seats and snoring... (Photo by Eric Lafforgue/Exclusivepix Media)

Thai office workers walk past armed soldiers standing guard outside the Shinawatra Tower Two in Bangkok, Thailand, 20 May 2014. Thai army Chief Prayuth Chan-ocha early on 20 May 2014, declared martial law giving the military full control to prevent further protest-related violence in the country. The statement was issued about 3 am on 20 May (2000 GMT), according to local media reports. Prayuth has the authority to declare martial law without the consent of the government, which has had caretaker status since 09 December 2013. Thailand has been wracked by six months of non-stop protests seeking to topple the government. At least 25 people have died in political-related violence and more than 700 injured. (Photo by Narong Sangnak/EPA)