|
WHAT TO SEE
Galilean moons
Io is the first of the four main moons of Jupiter. They are called the 'Galilean moons' because Galileo first spotted them through his telescope in 1610. The other three are called Europa, Ganymede and Callisto.
Volcanic plumes
Plumes of volcanic material spew out of Io's surface, shooting up to 300km high. The dark areas on the surface are eruption centres. They are surrounded by rings of ejected material and lava flows.
There are only three other places in the Solar System that definitely have volcanic activity: Venus, Earth and the Neptunian moon, Triton.
Why does Io have so many volcanoes?
In addition to the pull of Jupiter's gravity, Io also feels the strain from the gravitational fields of Jupiter's other large moons.
These multiple fields wrench Io's surface so fiercely that the whole globe can distort, stretching by up to 100km. Friction from this upheaval is responsible for much of Io's internal heat.
This creates molten lava underground, which then erupts violently through the surface.
SPOTTING IO FROM THE EARTH
Io can be seen from Earth through binoculars or with a small telescope.
 Consult our sky maps to find out what's in the sky this month
Like all moons, Io orbits around the planet Jupiter in a circular path. But from Earth, we see this orbit side-on. So as we watch, Io appears to move from side to side.
|
TRAVEL INFORMATION
Before you leave
Make sure you obtain an up-to-date map. The surface of Io is constantly reforming as molten rock erupts from its many volcanoes. In the 17 years between the Voyager and Galileo missions, one volcano moved 80km across Io's surface.
Giant electricity generator
Io's orbit cuts across Jupiter's powerful magnetic lines of force, turning Io into a giant electricity generator. Io can create currents of 3 million amps. This filters back down to Jupiter, creating lightning storms in the planet's upper atmosphere.
As Jupiter rotates, its magnetic field sweeps past Io and strips off about 1,000 kg (1 ton) of Io's material every second.
When you arrive
Many precautions must be taken when visiting such a harsh world. Landing on the surface is out of the question, with temperatures topping 1700ºC. The ground is made of solid sulphur dioxide - a deadly toxic acid.
Shape shifting
Be aware that Io is constantly changing shape. As with the Earth's moon, the same side of Io always faces Jupiter.
Explore Earth's moon
LOCAL HISTORY
In Greek mythology, Io was the daughter of a river god and a lover of Zeus. Jupiter is the Roman name for Zeus.
Zeus had lots of lovers and many of Jupiter's moons are named after them.
|
