What is Io?
Io is a moon of Jupiter. It orbits 262,000 miles away from Jupiter’s cloudtops. Io is 2250 miles in diameter making it a little larger than Earth’s moon. Q: What is so special about Io? A: Io has active volcanism. Io’s surface is littered with volcanoes with sizes from a mile to the size of the state of Arizona. The lava at these volcanoes streams for hundreds of miles from the volcanoes’ calderas (volcanic crater) and are much hotter than lava on Earth. In fact, the temperatures seen at some volcanoes are so hot that only the surface of the sun is hotter! The active volcanoes also cause towering plumes of sulfur and sulfur dioxide dust, snow, and gas. Some of these plumes can reach heights of 800 km and produce bright red rings on the surface like that seen at Pele and Tvashtar (the volcano seen above). In addition to have tons of active volcanoes, Io has some of the tallest mountains in the solar system. One mountain, Boosaule Montes, is 52,000 feet tall, 23,000 feet taller than Moun
Io is a moon of Jupiter. Along with Callisto, Europa, and Ganymede, Io is a Galilean moon, discovered by the Italian astronomer Galileo Galilei using one of the earliest telescopes. It is the innermost of the Galilean moons, exposing it closely to Jupiter’s powerful magnetosphere and ambient radiation. Due to tidal heating from its orbit around Jupiter, Io is one of the most geologically active bodies in the solar system, with over 400 volcanoes. When the Voyager spacecraft first saw evidence of volcanism on Io, it was the first discovery of volcanism on an extraterrestial world, and caused great excitement in the scientific community. Io’s unusual craterless surface caused it to be among the most fascinating of the Jovian moons to planetary scientists. Covered in sulfur and sulfur dioxide frosts, but with a thin silicate core, Io’s volcano-riddled surface makes it reminiscent of a yellow pizza. On Io’s trailing hemisphere, a huge volcano, Pele, eruptions constantly, surrounded by a gi
Io (eye-oh) is one of Jupiter’s four largest moons. Jupiter has lots of moons, but four of them – Io, Europa, Gannymede, and Callisto – are very large, and scientists were especially interested in learning more about them. 2 NASA scientists just happened to have a spacecraft already in the area. The Galileo spacecraft had been launched back in 1989 to learn as much as it could about Jupiter. Its main goals were to probe Jupiter’s atmosphere and to study Jupiter’s magnetosphere and its satellites. It was designed to be tough; it would have to be able to stand up to extreme levels of radiation. 3 Even before getting anywhere near Jupiter, Galileo began sending back useful information. It sent back data about Venus, Earth’s moon, and asteroids. When it reached Jupiter in 1995, Galileo sent back great pictures and interesting data. 4 The spacecraft was doing so well that its mission was extended. Galileo had already survived two to three times the amount of radiation that it was designed t
