Water frost detected on Mars volcanoes in ‘unexpected' first

The equatorial region of Mars is home to the solar system’s tallest volcanoes. The biggest one, Olympus Mons, stands at 16 miles (26 kilometers) high and 374 miles (602 kilometers) in diameter. The calderas on top of these volcanoes create a special microclimate where morning frost has been observed forming for the first time. The frost is thin but spread over a large surface area, amounting to an estimated 150,000 metric tons of water ice. The discovery of water frost in the equatorial regions of Mars was unexpected, as these regions are generally dry.