Competitors take part in the 8th annual World Gravy Wrestling Championships at the Rose n Bowl Pub in Bacup, north west England on August 31, 2015. Contestants must participate in fancy dress and wrestle in a pool of Lancashire Gravy for 2 minutes whilst being scored for a variety of wrestling moves. (Photo by Oli Scarff/AFP Photo)

Students pose for a picture with a 3- D optical illusion artwork of a devastated cityscape in Aleppo, Syria at the campus of the Meiji University in Tokyo on November 18, 2016. The Japanese branch of the human rights organisation Amnesty International displayed the artwork to encourage people to think about the Syrian civil war. (Photo by Toshifumi Kitamura/AFP Photo)

In this Wednesday, July 23, 2014 file photo, Omaha photographer Lane Hickenbottom photographs the night sky in a pasture near Callaway, Neb. With no moon in the sky, the Milky Way was visible to the naked eye. More than one-third of the world’s population can no longer see the Milky Way because of man-made lights, according to a scientific paper by Light Pollution Science and Technology Institute's Fabio Falchi and his team members, published on Friday, June 10, 2016. (Photo by Travis Heying/The Wichita Eagle via AP Photo)

A jogger runs along Bregagh Road at Dark Hedges, Armoy, Northern Ireland, Wednesday, February 10, 2016. Road markings have been painted by mistake on the world famous road that features the Dark Hedges tree lined road which was made famous by the Game of Thrones and is now a massive tourist attraction. (Photo by Peter Morrison/AP Photo)

A Colombian soldier hugs his girlfriend during the graduation ceremony of soldiers in Nilo, Colombia, February 17, 2017. The soldiers will be deployed to occupy territories formerly controlled by FARC rebels. (Photo by Jaime Saldarriaga/Reuters)

Indian folk dancers display ornaments during a break while participating in the first night of Navratri in Gandhinagar, some 30 km from Ahmedabad, on October 13, 2015. Navratri festivities, or Dance Festival of Nine Nights, takes place between October 13-21. (Photo by Sam Panthaky/AFP Photo)

Olaf Niess catches swans on the river Alster near the town hall in Hamburg, Germany, 17 November 2015. The Alster swans are moving to their ice-free winter quarters on the Eppendorf Muehlenteich millpond until spring. (Photo by Bodo Marks/EPA)

A participant in the Crazy Races extreme sports game competes in the cross-country obstacle race in Ufa, Russia on September 21, 2015. (Photo by TASS/Barcroft Media)