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)

(L-R) Young Paris, Lionel Richie, Isabela Moner and Austin Butler attend the Jeremy Scott Fashion Show during New York Fashion Week at Spring Studios on September 8, 2017 in New York City. (Photo by Ben Gabbe/Getty Images)

Protesters shield themselves as police beat them with sticks during a violent demonstration near the India Gate against a gang rape and brutal beating of a 23-year-old student on a bus last week, in New Delhi, India, December 23, 2012. The attack last Sunday has sparked days of protests across the country. (Photo by Kevin Frayer/Associated Press)

Workers sleep on a railway track under repair in New Delhi, India, June 15, 2018. (Photo by Saumya Khandelwal/Reuters)

Indian children dressed up as the Hindu deities Rama and Sita take a selfie photograph at an event to celebrate the Diwali festival in Ajmer in western Rajasthan state on November 6, 2018. (Photo by Shaukat Ahmed/AFP Photo)

Robert Galvan, who is on death row for murder, speaks to members of the media at the Adjustment Center yard during a media tour of California's Death Row at San Quentin State Prison in San Quentin, California December 29, 2015. America's most populous state, which has not carried out an execution in a decade, begins 2016 at a pivotal juncture, as legal developments hasten the march toward resuming executions, while opponents seek to end the death penalty at the ballot box. (Photo by Stephen Lam/Reuters)

Actress Zendaya arrives at the 27th Annual Kids' Choice Awards in Los Angeles, California March 29, 2014. (Photo by Danny Moloshok/Reuters)

“Himalayan Dog”. This dog just appeared out of nowhere and followed us for an entire week during our trekking trip in the Himalayan outback. He always used to sleep in front of our tent and guarded us in the nights. When I decided to get up at 4 a.m. to climb the next 5000 m peak for sunrise he accompanied me as well. On the top he was sitting for the entire 30 minutes on this place looking straight into the countryside. Photo location: Ladakh, India. (Photo and caption by Sebastian Wahlhuetter/National Geographic Photo Contest)