Click on image for full size
Image courtesy of NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute.
The Poles of Io
Io is the innermost of Jupiter's four large Galilean moons. Io is the most volcanically active object in our Solar System. It is no surprise, then, to find some of Io's 400 active volcanoes near the moon's poles. Two volcanoes, Tvashtar and Dazhbog, are close to Io's North Pole.
Both the Galileo and New Horizons spacecraft observed eruptions of the Tvashtar volcano. The Galileo spacecraft spotted a huge lava lake in the volcano's crater and also observed an eruption of a lava "curtain" that was 25 km (16 miles) long and at least a kilometer (three thousand feet) high! During its flyby of Jupiter in 2007, the Pluto-bound New Horizons spacecraft photographed an eruption plume from Tvashtar silhouetted against the edge of Io's disk.
The other volcano near Io's North Pole, Dazhbog, was observed by the Voyager spacecraft and by the Hubble Space Telescope. Dazhbog is named after a god from Slavic mythology. Tvashtar is named after the Hindu god of blacksmiths.
Io has a very thin atmosphere that mainly consists of sulfur compounds erupted from volcanoes. Io orbits Jupiter inside the planet's huge magnetosphere, where radiation particles are trapped within powerful magnetic fields. As radiation showers down onto Io's atmosphere, it causes atmospheric gases to glow. Io has aurora, but the celestial light shows on this strange moon are a bit different from the Northern Lights and Southern Lights we see on Earth. Io does not have a magnetic field to channel aurora-forming radiation particles to its polar regions. Instead, the aurora at Io glow most brightly around the moon's equator!
Shop Windows to the Universe Science Store!
Learn about Earth and space science, and have fun while doing it! The games
section of our online store
includes a climate change card game
and the Traveling Nitrogen game
You might also be interested in:
The Galilean satellites are the 4 major moons of Jupiter, Io, Europa, Ganymede, and Callisto. In this picture, Io, and Io’s surface, are shown on the left-most end, then Europa, and its surface, then Ganymede,...more
The Galileo spacecraft was launched on October 19, 1989. Galileo had two parts: an orbiter and a descent probe that parachuted into Jupiter's atmosphere. Galileo's primary mission was to explore the Jovian...more
The rare geometric arrangement of planets Jupiter, Saturn, Uranus, and Neptune in the 1980's made it possible for the Voyager spacecrafts to visit them over a 12 year span instead of the normal 30. They...more
The Hubble Space Telescope (HST) was one of the most important exploration tools of the past two decades, and will continue to serve as a great resource well into the new millennium. The HST is credited...more
Jupiter's magnetosphere is a unique object in the solar system. It is the biggest object in the entire solar system. Not only is it big enough to contain all of Jupiter's moons, but the sun itself could...more
One main type of radiation, particle radiation, is the result of subatomic particles hurtling at tremendous speeds. Protons, cosmic rays, and alpha and beta particles are some of the most common types...more
Radiation comes in two basic types: electromagnetic radiation transmitted by photons, and particle radiation consisting of electrons, protons, alpha particles, and so forth. Electromagnetic radiation,...more