Not a good spot for a holiday
(Image: NASA / JPL / University of Arizona)
POCKMARKED with sulphurous pits, bathed in intense radiation and shaken by constant volcanic eruptions, Io is the fiery hell of the solar system.
Despite being cold enough to be covered in layers of sulphur dioxide frost, this large inner moon of Jupiter is the most volcanic world known, spitting out 100 times as much lava as all Earth’s volcanoes can muster, from a surface area just 1/12th the size. Io’s surface is dotted with bubbling lakes of molten rock, the largest of which, Loki Patera, is more than 200 kilometres across.
Elsewhere, magma suddenly forces its way out of fissures in the rocky crust, creating lines of lava fountains that can stretch for 50 kilometres or more. NASA’s New Horizons spacecraft picked up the heat from one of these great curtains of fire in 2007 as the probe passed by Jupiter en route to Pluto.
Some of Io’s eruptions are violent enough to hurl giant plumes of gas and dust 500 kilometres into space. This can happen when a lava flow vaporises the surface layers of frozen sulphur dioxide, or when dissolved gas turns to bubbles inside rising magma and blasts high-speed debris out through the moon’s surface.
All this volcanic violence results from a tug of love between Jupiter and Io’s two siblings, Europa and Ganymede. These moons have orbital periods exactly 2 and 4 times as long as Io’s, which results in the three moons lining up every so often. Over time, the gentle gravitational tugs of this periodic conjunction have gradually nudged…
