A Saudi soldier fires a mortar towards Houthi movement position, at the Saudi border with Yemen April 21, 2015. (Photo by Reuters/Stringer)

The possible surface of TRAPPIST-1f, one of seven newly discovered planets in the TRAPPIST-1 system that scientists using the Spitzer Space Telescope and ground based telescopes have discovered. (Photo by Reuters/NASA/JPL-Caltech)

Zoee Heath of New South Wales competes in the womens U18 discus throw during day two of the Australian Junior Athletics Championships at Sydney Olympic Park Athletic Centre on March 11, 2011 in Sydney, Australia.

A Boeing 777-300 from Swiss International Airlines lands on a foggy morning at Zurich Airport, on Friday, October 13, 2017, in Zurich, Switzerland. The high humidity renders the air vortex visible. (Photo by Christian Merz/Keystone via AP Photo)

Enthusiasts gathered at Cad East in Snowdonia National Park, England to take pictures of F-15 Eagle fighters as they completed the Mach Loop, November 2017. (Photo by Caters News Agency)

Team Alberta skip Kevin Koe makes a shot during the 10th draw against team British Columbia at the Brier curling tournament in Brandon, Manitoba, Tuesday, March, 5, 2019. (Photo by Jonathan Hayward/The Canadian Press via AP Photo)

View of the Villarrica volcano taken from Pucon, some 800 kilometres south of Santiago, showing signs of activity on December 06, 2017. (Photo by Christian Miranda/AFP Photo)