Overview of Io
Io is the innermost of the four large moons of Jupiter known as the Galilean satellites. Io is a little larger than the Earth's moon but has a surface that couldn't be more different. While the ancient surface of our moon is dominated by impact craters and large basalt "mare" provinces that are 3-4 billion years old, Io's surface is continuously being renewed, with more than 400 volcanic depressions known as a paterae and more than 130 mountains, the vast majority of which are created by tremendous compressional stresses in Io's crust. The engine for this violent volcanic activity is tidal heating. Io's orbit is slightly eccentric and Jupiter's gravitational pull on Io varies over the course of an Ionian day. The moons Europa and Ganymede help to prevent Io from circularizing its orbit, keeping the heat engine in Io's mantle running.
For more information on Io and its volcanism, check out the following links:
- On Wikipedia, check out the Io and Volcanism on Io articles. Both are featured articles on the online encyclopedia, representing some of the best content there. Plus, I regularly review content changes to those articles in order to maintain their high quality. I am also beginning to prepare more articles on several of Io's volcanic features, such as Pele, Masubi, and Tawhaki Vallis.
- Janet Wood created a neat site about 10 years ago on Io that is still helpful for providing an overview of Io science called Io: Jupiter's Volcanic Moon
- The USGS has a website dedicated to planetary nomenclature, or surface feature names. Their section on Io provides a list of official names used for volcanoes and mountains on Io.
- Looking for a map of Io? Scientists at the USGS office in Flagstaff created a basemap based on Voyager and Galileo images of the satellite several years ago. Several versions of this map can be found on their website as well as a PDF version of the color basemap with feature names added.
- Looking for images from the Voyager, Galileo, or New Horizons spacecraft? A good place to look for officially released versions of spacecraft images is the Planetary Photojournal, which has a page for Io images. I also have a page where I've done my own processing of the raw data from Voyager, Galileo, and New Horizons.
While generally I post articles related to recent news or the latest papers, from time to time I also post articles that provide an overview of a topic of Ionian research, whether it is on the formation of Io's volcanoes or the composition of its surface. I believe these articles are of the most interest to new readers, so I've listed a few of them here:
- Formation of Paterae (volcanic craters) on Io
- Formation of Mountains on Io
- The Chemical Composition of Io
- Boösaule Montes: The Tallest Mountain on Io
- The Curious Case of Reiden Patera
- It's Not Easy Being Green: The Chaac Patera Story
- Io@400: A series of posts covering Galileo Galilei's Discovery of Io in 1610
- Astronomy from Io
- The Potential for Science at Io from the upcoming Juno mission
- Summary of the proposed Io Volcano Observer mission
- The Potential for Science at Io from the upcoming Europa/Jupiter System Mission