In this October 21, 2015, file photo, a young man rides a hoverboard along a Manhattan street toward the Empire State Building in New York. More than 500,000 hoverboards are being recalled after reports that they can burst into flames. The Consumer Product Safety Commission said Wednesday, July 6, 2016, it has received 99 reports of battery packs in the two-wheel motorized scooters catching fire or exploding that causing burns or property damage. The recalled hoverboards were made by eight companies. (Photo by Kathy Willens/AP Photo)

Students celebrate their A-level results at King Edward VI High School for Girls in Birmingham, England on August 18, 2016. The proportion of top grades achieved by A-level students across the UK has fallen for a fifth year in a row, and girls have caught up with boys in attaining A* grades. (Photo by Joe Giddens/PA Wire)

One of the worlds shortest models Mary Russell at 4 feet 1 inch with 6 foot model Georgia Meacham in London, UK on June 16, 2016. The 4ft1 beauty suffers with achondroplasia a medical term for dwarfism, which means she has as average sized torso but short arms and short legs, with an oversized head. As well as stifled growth, Mary also suffers with sciatica and spinal stenosis, an abnormal narrowing of the spinal canal – which cause agonising nerve problems, leaving her in excruciating pain and unable to stand for long periods of time. The condition leaves Mary, 47, struggling with everyday tasks things most people take for granted like going to the supermarket, getting cash from an ATM and ordering a drink at a bar become a challenge. (Photo by Simon Jacobs/Caters News Agency)

Revellers pose during the 24th Street Parade dance music event in Zurich, August 29, 2015. (Photo by Arnd Wiegmann/Reuters)

Two men play golf with a tennis ball as a snowstorm sweeps through Times Square, Tuesday, March 14, 2017, in New York. (Photo by Mark Lennihan/AP Photo)

Hostesses pose in front of a Suzuki Ignis car at the European Motor Show in Brussels, Belgium, January 13, 2017. (Photo by Francois Lenoir/Reuters)

A picture made available on 13 May 2016 shows A Tiwa girl performing her traditional dance as they celebrated the Wanchuwa festival in Karbi Anglong District of Assam state, India, 11 May 2016. Wanchuwa is one of the most important festivals of the Tiwa tribal community living in the hills as it is related with agriculture which is the mainstay of their economy. Tiwas pray for a bountiful harvest during this festival and to protect their crops from pest and other natural calamities. Tiwa is a major tribe of Assam state who practice Jhum or shifting cultivation for their living in the hills. (Photo by EPA/Stringer)

Wedges of an orange generate enough current and electrical juice – 3.5 volts – to power an LED. The fruit’s citric acid helps electrons flow from galvanized nails to copper wire in this 14-hour exposure. This image was published in September’s Visions of Earth, a trio of photos that appear in each issue of National Geographic. (Photo by Caleb Charland/National Geographic)