Whole Object Name
Io Scale Model
Scale model of Jupiter’s moon Io. It is a 1:100,000,000 scale model, based on an estimate of Io’s diameter to be 3,630 kilometres. Io was first discovered by Italian astronomer Galileo Galilei and is one of Jupiter's four largest moons. Named after their discoverer, the Galilean moons consist of Ganymede, Callisto, Io and Europa in descending size order.
Io is the most volcanic body in the solar system and this intensive activity has caused the colourful chaotic appearance of its surface. Io completes an orbit of Jupiter every 42.5 hours and is the closest of the four Galilean moons to the gas giant. This proximity to the Solar System’s largest planet, along with the impact of the other Galilean moons, means that Io is under huge gravitational stresses. As Jupiter's gravity pulls on the near face of Io, the other Galilean moons pull it in other directions. The result is that Io's shape is distorted. Io's orbit is also distorted and highly eccentric as a result, which in turn means that Io's shape is constantly changing. All of this distortion leads to a lot of friction in Io, causing a great deal of heat which drives the volcanic activity on the surface - a process known as tidal heating. This theory of why Io has so many volcanoes is widely accepted, but recent scientific investigation has raised a few anomalies as to how the volcanoes are distributed across the surface. Other theories have sought to account for the anomalies, such as the idea that Io also has an ocean of molten rock under its surface - producing extra heat from this magma ocean, as its mix of molten and solid rock flows and rubs against other rocks.
Io's volcanoes - some of which are taller than Mount Everest - are so active that the surface of the moon undergoes constant change. When Voyager 1 sent back its first images of Io scientists were expecting to see lots of impact craters, like those seen on the surface of the Earth's Moon. Instead the surface was largely smooth, with volcanoes, mountains, lava flows and pits. The volcanic activity buries craters after they are produced by meteorite strikes, and therefore the surface of Io is considered geologically young. The unusual colouring of the surface - as depicted on the high-fidelity model - is a result of sulfurous compounds deposited by the volcanic activity.