Jupiter's moon Io
Jupiter’s moon Io orbits 217,000 miles above the swirling storms of the giant of the solar system. Io is a fiery landscape of Hell…extreme heat, erupting volcanoes, plains of yellow sulphur, and lakes of molten lava. Even the ground itself is in motion, rising, falling and splitting apart. The tiny moon Io, one of the four main moons of Jupiter (it has 62 in all) and the closest of the four to the giant planet. Io is the most geologically active place in the solar system. On a body little bigger than Earth’s Moon Io has more than 400 active volcanoes, spewing out sulphur and sulphur dioxide as high as 310 miles into space and raining down as sulphur snow. Some of this material doesn’t fall to the surface, but keeps on going out into deep space and even accelerating. The temperature inside the volcano vents unbelievably can be 1/3rd the temperature of the surface of the Sun, yet the temperature over the normal land of Io is a bone chilling -150 degrees C. Vast mountains twice the height of Everest look down on a weird landscape of yellow, black and orange sulphur plains that make the whole moon look like a cheese pizza.
Jupiter is huge, bigger than all the planets put together so the gravitational pull on Io is immense. The tiny moon takes a gravity battering from Jupiter and is heated to extremes from the inside out. Io is pulled and tugged out of shape by the giant planet, and due to Io’s elliptical orbit it comes in closer at some times than others. So Io is always in a state of flux, being stretched and compressed. So much so that it actually has land tides. On Earth we have sea tides from the pull of the Moon’s gravity, on Io the land itself rises and fall by as much as 100 metres. On Earth the biggest water tide difference is just 18 metres.
Two sulphurous eruptions seen from the Galileo spacecraft at 373,000 miles away. The one on the outer limb rises 140 km from the Pillan Patera caldera. The one in the centre is the 75 km high Prometheus Plume that has been in continious eruption for 18 years
This keeps the interior of Io completely molten and at very high temperatures, causing constant volcanic eruptions. Io has no impact craters from meteorites or comets because the surface is always young. Any craters will quickly be covered over by lava or sulphur.
Jupiter has a huge magnetic field that goes out to nearly the orbit of Saturn. as the giant planet rotates the magnetic field rotates with it, ripping off 1 tonne of material from Io every second. This material forms a doughnut shaped plasma torus when it becomes ionized in the magnetic field. This plasma encircles Jupiter along Io’s orbit. As Io goes through the planet’s magnetic field lines another effect is created, electricity is generated across Io of around 40,000 volts, and a huge electric current. This current of 3 million amps can flow along Jupiter’s magnetic field lines and down to the planet, producing lightening bolts in Jupiter’s atmosphere…a truly dynamic and amazing system.
In 2001 Nasa’s Galileo Spacecraft made several very close passes of Io, including flying through a volcanic eruption plume. But hot embers weren’t what Galileo detected, instead it was snow, sulphur dioxide snow. The volcanic vents that the gases are coming out of are extremely hot, but as soon as the gas hits the frigid cold of space it freezes the sulphur dioxide gas to create snow.
Io's volcano Ra Patera from Voyager showing the caldera vent and lava flows 200 miles long.
Unlike one or two of Jupiter’s other moons, Io has very little or no chance of hosting any kind of life as the place is just too hostile and extreme. Io has a weak atmosphere but is well within Jupiter’s powerful magnetosphere and is constantly bathed in lethal radiation. This atmosphere offers little protection. Also Io is both extremely hot and extremely cold, together with being covered in sulphur and lava. Any kind of life would have to be pretty tough indeed.
The Jovian system is like a solar system in miniature, and each moon has its own special uniqueness. Jupiter and it’s moons Io, Europa, Callisto, and Ganymede can easily be seen in the smallest of telescopes or even binoculars. The four moons can be seen stretched out from Jupiter’s disk like a string of pearls that constantly shift and change position. The moon Io is just one of the of incredibly interesting satellites that inhabit our solar system.
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