These Arab recruits line up in a barracks square in the British Mandate of Palestine, on December 28, 1940, for their first drill under a British solider. Some 6,000 Palestinian Arabs signed up with the British Army during the course of World War II. (AP Photo)

A fledgling solar system containing deep within it enough water vapor to fill all the oceans on Earth five times, located in our Milky Way galaxy about 1,000 light years from Earth in the constellation Perseus. (Photo by Reuters/NASA/JPL-Caltech)

In this Tuesday, December 20, 2016 photo, Mohammad Ramzan, right, reacts while talking to The Associated Press with his young bride Saima in Jampur, Pakistan. Saima was given as a bride to the older man by her father so he could marry the groom’s sister, a practice of exchanging girls that is entrenched in conservative regions of Pakistan. It even has its own name in Urdu: Watta Satta, “give and take”. A mix of interests – family obligations, desire for sons, a wish to hand off a girl to a husband – can lead to a young teen in an a marriage she never sought. (Photo by K.M. Chaudhry/AP Photo)

Children hold signs thanking truck drivers hauling rocks to the Lake Oroville Dam after an evacuation was ordered for communities downstream from the dam in Oroville, California, U.S. February 13, 2017. (Photo by Jim Urquhart/Reuters)

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)

A monkey leaps into a pond on a hot day in Allahabad on May 19, 2017. According to local reports temperatures have soared in the northern Indian city to 47.28 Celsius. (Photo by Sanjay Kanojia/AFP Photo)

A young boy plugs his ears as his sister (C) and nanny (L) watch from Gravelly Point Park as planes land at Reagan National Airport in Arlington, Virginia on June 29, 2017. President Donald Trump' s travel ban on people from six mostly Muslim countries will come into force late Thursday, as controversy swirls over who qualifies for an exemption based on family ties. (Photo by Jim Watson/AFP Photo)

A bonnet macaque sits on consecrated idols of snakes as it drinks milk offered by a devotee during the Hindu festival of Nag Panchami, which is celebrated by worshipping snakes to honour the serpent god, inside a temple on the outskirts of Bengaluru, India, July 27, 2017. (Photo by Abhishek N. Chinnappa/Reuters)