An infrared portrait from NASA's Spitzer Space Telescope which shows generations of stars is seen in this undated NASA handout image released February 14, 2013. In this wispy star-forming region, called W5, the oldest stars can be seen as blue dots in the centers of the two hollow cavities (other blue dots are background and foreground stars not associated with the region). Red shows heated dust that pervades the region's cavities, while green highlights dense clouds. (Photo by NASA/Reuters/JPL-Caltech/Harvard-Smithsonian/Handout)

A member of the Tinstix of Dynamite aerobatics team flies in front of a wall of fire during the Australian International Airshow in Melbourne on March 5, 2017. The annual event sees 180,000 visitors over the 3-day public event held at the Avalon Airfield some 80kms south-west of Melbourne. (Photo by Mal Fairclough/AFP Photo)

A woman carries earthen pots to fill them with drinking water on a hot summer day, on the outskirts of Ajmer, Rajasthan, India April 25, 2017. (Photo by Himanshu Sharma/Reuters)

A photo taken by a member of the County Durham and Darlington fire and rescue Service of a coach on fire on the A1 in County Durham, England on March 2, 2017. Passengers were evacuated safely before flames engulfed the vehicle. (Photo by County Durham and Darlington Fir/PA Wire)

Confiscated rare and protected wildlife products such as these stuffed Sumatran tiger skins are burned and destroyed during a ceremony by government forestry and wildlife officials in Banda Aceh, Aceh province, Indonesia May 23, 2016 in this photo taken by Antara Foto. (Photo by Irwansyah Putra/Reuters/Antara Foto)

A man takes a shower on a street from water coming from a drainpipe as it rains in Havana, Cuba, Wednesday, July 27, 2016. During the last couple of weeks short but intense tropical downpours have been coming down of Havana every afternoon. (Photo by Desmond Boylan/AP Photo)

Men selling sheep wait for customers at a local livestock market, ahead of the Eid al-Adha festival, in Lagos, Nigeria September 11, 2016. (Photo by Akintunde Akinleye/Reuters)