Massive lava tubes on the moon and Mars could be used by astronauts

(CNN)Lava tubes beneath the surface of Mars and the moon could be, respectively, 100 and 1,000 times wider than lava tubes on Earth, which could provide shelter and create exploration opportunities for astronauts in the future, according to a new study. Lava tubes are caves created by lava as it flows from a volcanic vent beneath a hardened surface. On Earth, these lava tubes can be found in Hawaii, the Canary Islands, Australia and Iceland. They range in diameter from 33 to 98 feet. Lunar tubes on the moon and Mars could be longer than 25 miles, according to a new study using satellite images, radar data, spacecraft observations of features called skylights belonging to collapsed lava tubes...