March 8 will bring us what is called “Jupiter at Opposition.” This means the giant planet will be at its closest approach to Earth and its face will be fully illuminated by the Sun. Jupiter will be brighter than any other time of the year and will be visible all night long. It will be seen on the eastern horizon after sunset under the constellation Leo, the lion.
There has been lots of talk in Baton Rouge about ice, snow, and cold. Let’s change focus and talk about something hot: volcanoes! The planetarium is about to debut its latest show “Super Volcanoes” which gives audiences a front row seat to some of Earth’s largest volcanic eruptions. The show features extensive live action footage of geothermal features in Yellowstone National Park, as well as a complex simulation of an eruption of the Solar System’s largest active volcano, Loki.
Loki can be found on Jupiter’s moon Io. Named for the Norse God of Mischief (or comic book villain if you prefer), this volcano is considered to be the hottest and most powerful in the Solar System. Loki is officially called Loki Patera which means “Loki Basin”. Loki is not a tall volcano, it has no cone. It is the opposite, a large depression in Io’s surface that is filled with lava. Loki alone puts out more heat than all of Earth’s volcanoes combined!
Volcanism was discovered on Io by Voyager back in the 1970s. Up until this point people thought Earth was the only place with such active geology. Initially it was surprising to discover this much activity on such a tiny world. Scientists thought that since larger bodies (such as the other rocky planets, and larger moons) appeared to have thoroughly cooled and stopped exhibiting signs of active volcanism, tiny bodies such as Io wouldn’t exhibit it either. Voyager snapped photos of Io’s surface, showing large volcanic scars as well as plumes of ash reaching into the skies. Io had even more volcanic activity than Earth!
So why is this? As we rub our hands together to stay warm in this winter weather we’re having here in Baton Rouge, consider the moon Io. Io orbits closest to Jupiter out of the four largest moons. The combination of tidal forces from Jupiter, tidal forces from the other large moons, as well as the shape of Io’s orbit all play a role. The constant tugging on Io is thought to cause friction and internal heat inside the moon. Kind of like when you rub your hands together but a lot more so!
Io has mountains and plains, as well as different types of volcanoes. Loki is thought to be a large lake of lava. Images taken from spacecraft show a large dark depression (almost 130 miles across!) with steep edges. Thermal studies have shown that the surface is extremely hot, likely due to a large pool of lava covered by a thin crust. The crusts of these lava lakes can become disrupted, triggering a wave across the lake. The denser crust sinks below the molten rock beneath causing the lake to resurface itself. Scientists are still unsure about how Loki-type volcanoes form on Io. They could form from a collapsed volcano (this occurs on Earth and they are known as Caldarae), or they could be created from an impact of a large meteor into the surface.
Images of spacecraft have also shown plumes of volcanic material being ejected from Loki that have reached nearly 150 Km above the surface (that’s higher than the International Space Station orbits above Earth!). In “Super Volcanoes” audiences will travel to Loki and witness what this eruption might look like from the surface!
If you haven’t already, check out the trailer for “Super Volcanoes”, opening February 1 at the Irene W. Pennington Planetarium.