Revelers of the Holi Festival of Colors dance after throwing colored powders in the air in Madrid, Spain, Saturday, August 9, 2014. The festival is fashioned after the Hindu spring festival Holi, which is mainly celebrated in the north and east areas of India. (Photo by Daniel Ochoa de Olza/AP Photo)

Sunrise over Maridalsvannet in the forest areas near the outskirts of Oslo, the capital of Norway. Winter is approaching, the first snow covers the ground, and the water has already got a thin layer of ice. The temperature is significantly below the freezing point, the air is clear and the sun colors the morning clouds in deep tones. (Photo by Tore-Thiis-Fjeld/Getty Images)

Virgin Galactic's new spaceship N202VG (bottom L) is seen behind the WhiteKnightTwo carrier aircraft mothership (front), which landed safely after splitting from SpaceShipTwo, in a hangar at Mojave Air and Space Port in Mojave, California, November 4, 2014. (Photo by Lucy Nicholson/Reuters)

A Palestinian fighter from Ezz-Al Din Al-Qassam Brigades, the armed wing of the Hamas movement, checks debris at the site of an Israeli air strike in Khan Yunis in the southern Gaza Strip on December 26, 2019. (Photo by Said Khatib/AFP Photo)

A hot air balloon in the shape of children's comic Rupert Bear is seen tethered before a tethered flight at the Bristol International Balloon fiesta in south west England, Britain, August 10, 2018. (Photo by Adrian Sherratt/The Guardian)

Yuchen Chao of Chinese Taipei in action during the Beach Handball Women's Tournament match between Chinese Taipei and Paraguay at The Beach Handball Arena, Tecnopolis Park, Buenos Aires, Argentina, October 12, 2018. (Photo by Lukas Schulze for OIS/IOC/Handout via Reuters)

Vehicles pass through the heavy fog and air pollution that cover Skopje valley in the early morning, in Skopje, The Former Yugoslav Republic of Macedonia, 14 December 2017. According to media reports, Skopje is considered one of the most polluted cities in the world. (Photo by Georgi Licovski/EPA/EFE)

Aegean airlines air hostesses take selfies after a news conference in Athens, Wednesday, March 28, 2018. In a deal worth up to $5 billion, Greek airline Aegean says it will buy 30 new Airbus aircraft, with the option of an additional 12, to upgrade its fleet as the country expects to break tourism records. The signing of the final purchase agreement is expected in June. (Photo by Petros Giannakouris/AP Photo)