The image above depicts Jupiter and its moon, Io. The tiny red dot on the surface of Io is a volcano, while the blue above it is the volcanic emissions. According to NASA, "The Io image, taken on March 1st 2007, is an approximately true-color composite taken by the panchromatic Long-Range Reconnaissance Imager (LORRI), with color information provided by the 0.5 µm (“blue”) and 0.9 µm (“methane”) channels of the MVIC."
Since Io 's discovery by Galileo in 1610, it has continuously been both confusing and amazing scientists. First of all, it's larger than our own moon, and is also the most volcanically active object in the solar system. Io is home to volcanoes that erupt liquid sulfur dioxide, and has a molten iron/iron sulfide core due to the immense tidal heating associated with orbiting so closely to Jupiter at roughly 350,000 km. This happens because the gravitational field of Jupiter is so powerful that it squeeze Io, and that the magma inside Io is pushed outside because of the amount of pressure it induces.
The magnetosphere of Jupiter sucks off the dust and gasses emanating from Ionian eruptions at a rate of about 1 tonne per second. It has no magnetic field of its own, but instead has a magnetosphere created by Jupiter's. This is turn induces an electrical current along the magnetic lines of force from Jupiter's north pole, through Io, and back to Jupiter's south pole, which in turn creates an auroral glow similar to Earth's aurora. It's orbit is encased in a plasma torus of high-energy radiation and ionized sulfur, sodium, oxygen, and chlorine. Io's orbit is eccentric, since Io has the moons Europa, Ganymede, and Callisto pulling it back.
