Jupiter's moon Io is the most volcanically active planetary body in the solar system. Amidst its hundreds of volcanoes and lava lakes, scientists now believe they've encountered a powerful type of eruption seen for the first time on a body other than Earth: a Stromboli-like eruption.
The data is a blast from the past, coming from NASA’s Galileo orbiter which explored the Jupiter system from 1995 through 2003. Even though Galileo burned up in Jupiter's atmosphere 14 years ago, its sent back so much data that scientists are still sifting through it.
Meant to study and map the distribution of surface minerals and cloud morphology on Jovian moons, the NIMS detected what NASA-JPL scientist Ashley Davies as "a very short-duration, highly-changeable, powerful thermal event."
Looking through NIMS data, Davies and her colleagues noticed a heat signal jump to 4–10 times higher than background levels. A minute later, the signal dropped around 20 percent. Another minute passed and the signal plummeted another 75 percent. Twenty-three minutes later, heat signals returned to background levels.
The event was similar to a Strombolian volcano eruption on Earth. Strombolian volcanoes are named after the Italian island of Stromboli and produce . However, these eruptions do produce dramatic explosions that hurl molten lava fragments into the air without producing a lava flow. They look like this.
These relatively weak eruptions on Earth are considered quite powerful on Io. On the 2236-mile wide moon (3500 km), eruptions occur "on a scale that simply isn’t seen on Earth today but was once common in Earth’s past," Davies says.
The masses of tiny particles that a Strombolian volcano sends into the air rapidly cool. The way lava cools effects what types of rock are produced, which in turn transforms the makeup of Io's surface. That composition can then tell scientists about Io's interior layers as well.
“Instead of being a completely fluid layer, Io’s magma ocean would probably be more like a sponge with at least 20% silicate melt within a matrix of slowly deformable rock,” Christopher Hamilton, a planetary volcanologist not involved with the study.
Even this volcano-ridden hellscape has more to it than meets the eye.