Girls practice sit-ups during gymnastics lessons at the Shanghai Yangpu Youth Amateur Athletic School in Shanghai, China, on May 4, 2016. China's sports system has been enormously successful since the country returned to the Olympic fold in 1980, culminating with the host nation topping the medals' table at the 2008 Beijing Olympics. And yet, with the Rio de Janeiro Games less than three months away, the system is beginning to break down due to the shifting demographics of a more prosperous nation. (Photo by Aly Song/Reuters)

A member of the riot police gets ready to repel the attacks of protesters during a protest against President Sebastian Piñera during the seventh day of protests against President Sebastian Piñera on October 24, 2019 in Santiago, Chile. Although President Sebastian Piñera announced measures to improve equality, unions called for a national strike and demonstrations continue as casualties are now at least 18. Demands behind the protest include issues like health care, pension system, privatization of water, public transport, education, social mobility and corruption. (Photo by Marcelo Hernandez/Getty Images)

The Waitomo Glowworm Caves attraction is a cave at Waitomo on the North Island of New Zealand, known for its population of glowworms, Arachnocampa luminosa. This species is found exclusively in New Zealand. They are around the size of an average mosquito. This cave is part of the Waitomo Caves system that includes the Ruakuri Cave and the Aranui Cave.

Rhodochrosite is a manganese carbonate mineral with chemical composition MnCO3. In its (rare) pure form, it is typically a rose-red color, but impure specimens can be shades of pink to pale brown. It streaks white, and its Mohs hardness varies between 3.5 and 4. Its specific gravity is between 3.5 and 3.7. It crystallizes in the trigonal system, and cleaves with rhombohedral carbonate cleavage in three directions.

Axel, a research prototype rover for exploring the Moon, Mars and other planets, is remotely driven over rocks as engineers from Jet Propulsion (JPL) and grad students from Caltech (California Institute of Technology) demonstrate its mobile over the steep and rocky grounds of the JPL Mars Yard on January 14, 2009 in Pasadena, California. The rover is capable of descending cliffs or into craters and returning by a cable tethered to its starting point. Development of the Axel rover is a point effort funded by NASA Exploration Systems Mission Directorate (ESMD) and lead by Principal Investigator Issa Newnas and Co-Investigator and Caltech professor of mechanical engineering bio engineering Joel Burdick. (Photo by David McNew/Getty Images)

Bex Hetherington exhibits a T-shirt at the Edinburgh College of Art degree show on June 8, 2011 in Edinburgh, Scotland. Students work will be exhibited across the campus buildings turning Edinburgh College of Art into the city's biggest gallery space. The work ranges from conceptual to commercial with inspirational influences as diverse and wide ranging as fashion photography, volcanoes, the crazy lady who put a cat in a bin, fairytales, the star system and serial killers. (Photo by Jeff J Mitchell/Getty Images)

A protester holds a sign in front of riot policemen during an anti-G20 demonstration through the streets of Nice on November 1, 2011 in Nice, France. Anti-G20 demonstrators are gathered in Nice ahead of the arrival of the world's top economic leaders for the G20 summit in Cannes on November 3rd and 4th. The leaders are expected to debate current issues surrounding the global financial system in the hope of fending off a global recession and finding an answer to the Eurozone crisis. (Photo by Christopher Furlong/Getty Images)