New photos of Mercury's mysterious north pole reveal a glimpse of the permanently dark, frigid craters that may hold ice dozens of feet thick, even though Mercury is the closest planet to the sun.
Mercury's surface can reach a blistering 800 degrees Fahrenheit (430 degrees Celsius) during the day, according to NASA. But the planet lacks an atmosphere to hold that heat in — so, on Mercury, dark equals cold. At night, temperatures can plunge to minus 290 F (minus 180 C). The planet's north pole is pockmarked by craters whose bottoms are always in shadow. Research has shown that these crater bottoms likely contain thick deposits of water ice.
