An injured fan is helped by a riot policeman during clashes between Red Star Belgrade and Partizan Belgrade fans in the stadium before the teams' Serbian Superliga soccer match in Belgrade, April 25, 2015. Serbian league leaders Partizan Belgrade held champions and bitter city foes Red Star to a 0-0 draw in a derby match marred by bad crowd trouble before kickoff on Saturday. The start was delayed for 45 minutes after home Red Star supporters pelted riot police with seats and flares, forcing officers to retreat from the north tier that houses the club's diehard fans. (Photo by Marko Djurica/Reuters)

In this Monday, July 20, 2015 photo, Bill Lattin, the Southern California Timing Association president and Speed Week race director, stands in the Bonneville Salt Flats in Utah. A small city of tents, trailers and thousands of visitors appears almost every August in the Utah desert to watch cars, motorcycles and anything with wheels rocket across gleaming white sheets of salt at speeds of 400 mph. But wet weather has forced the cancellation of Speed Week for the second straight year and revived a debate about whether nearby mining is depleting the Bonneville Salt Flats of their precious resource. (Photo by Rick Bowmer/AP Photo)

Policemen guard Poland's Supreme Court as a protester lies on the pavement in Warsaw, Poland, on Thursday, April 22, 2021. A disputed disciplinary body within Poland's Supreme Court is examining a motion that could result in the arrest of a judge who has become a symbol of the fight for an independent judiciary. (Photo by Czarek Sokolowski/AP Photo)

Jacob's Well is a perennial karstic spring in the Texas Hill Country flowing from the bed of Cypress Creek, located northwest of Wimberley, Texas. The twelve foot (four meter) diameter mouth of the spring serves as a popular swimming spot for the local land owners whose properties adjoin Cypress Creek. From the opening in the creek bed, Jacob's Well cave descends vertically for about thirty feet (ten meters), then continues downward at an angle through a series of silted chambers separated by narrow restrictions, finally reaching a depth of one hundred and twenty feet (forty meters). Until the modern era, the Trinity Aquifer-fed natural artesian spring gushed water from the mouth of the cave, with a measured flow in 1924 of one hundred and seventy gallons per second (six hundred and forty liters per second) discharging six feet (two meters) into the air. The spring is the greatest source of water recharging the Edwards Aquifer.

NASA says it could be another 20 years before humans touch down on Mars, but in a sense, the Mars Society has been exploring the red planet for more than a decade – in Utah. Photo: Csilla Orgel, a geologist of Crew 125 EuroMoonMars B mission, makes her way back to the Mars Desert Research Station (MDRS) in the Utah desert March 3, 2013. The MDRS aims to investigate the feasibility of a human exploration of Mars and uses the Utah desert's Mars-like terrain to simulate working conditions on the red planet. Scientists, students and enthusiasts work together developing field tactics and studying the terrain. All outdoor exploration is done wearing simulated spacesuits and carrying air supply packs and crews live together in a small communication base with limited amounts of electricity, food, oxygen and water. Everything needed to survive must be produced, fixed and replaced on site. (Photo by Jim Urquhart/Reuters)

The buffalo bull charges, on March 23, 2014, in Addo Elephant National Park, South Africa. A young elephant calf tried to attack an old buffalo bull and was taught a lesson it will never forget. The calf was with its herd at a watering hold Addo Elephant National park, South Africa, when the buffalo ventured towards the water. The elephant ran towards the buffalo but the larger animal picked up the young calf and tossed it four metres in the air. Luckily, the elephant was not hurt, but its pride was seriously injured. (Photo by Conrad Cramer/Barcroft Media)

Chinese artist Kong Ning walks in her costume made of hundreds of orange plastic blowing horns during her art performance raising awareness of the hazardous smog in front of the Drum tower in a historical part of Beijing on a very polluted day December 7, 2015. Kong, whose works include themes related to China's air pollution problem, named her new performance “The Orange Horns Bride Marries the Blue Sky” and presented it dressed in orange, the colour of the second highest pollution alert level issued again in Beijing as hazardous smog blankets the capital. (Photo by Damir Sagolj/Reuters)