Published on May 16th, 2014 | by Bridget Murray


Io and behold

Have you picked up your copy of Issue 10 yet? If you don’t have one, fear not; you can read it online.

If you have been lucky enough to read the magazine already, you may have noticed a mystery picture on the first page. In our editorial we challenged you to work out what it was, and its (tenuous) link to 10…

The Moon

photo 2I can now reveal that the beautiful picture (courtesy of NASA) is of Io – the innermost of Jupiter’s four Galilean moons. It’s also the most geologically active object in the solar system, with over 400 active volcanos spotted over its surface. This unusual state is a product of Io’s elliptical orbit, which positions the moon at varying distances from Jupiter at different stages of its orbit, which results in enormous tidal forces. The forces cause the surface of the moon to bulge in and out whilst generating so much heat that the subsurface crust of the moon remains in a liquid form. The liquid escapes to the surface any way it can to reduce pressure, which leads to volcanos. The composition of the liquid is still under debate — it isn’t lava as we know it on Earth. Some argue it’s molten sulphur, others that it’s molten silicate rock. Regardless, it’s this volcanism that makes Io so unique. Volcanic plumes and lava flows mark the surface, giving Io its marbled look.

Discovery of Io

photo 4Galileo Galiliei discovered Io on the 8th January 1610. Along with the three other Jovian moons, the discovery of Io marked the first time any planet other than Earth was known to have a moon orbiting it. The name Io was assigned in the mid 1800s, replacing Galileo’s original, and less exciting, Jupiter 1. Despite its early discovery, until the late 19th Century Io was just a point of light. Technological advances allowed greater resolution, and astronomers were able to identify large surface features, including its bright equator and dark polar regions. It wasn’t until 1979 that two Voyager space craft passed by and revealed the unique geological nature of the moon. Since then, close fly by inspections have allowed us to learn more about the moon; its interior, its rapidly replenishing surface and the relationship between Jupiter’s and Io’s magnetospheres.

Research continues to this day to uncover as many of this mysterious moon’s secrets as possible.

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About the Author

A zoology undergraduate in her fourth year, Bridget spends most of her time trying to pretend graduation isn't looming, fiddling with the exhibitions in the Zoology Museum. In her spare time she bakes a lot of cakes and edits a lot of words.

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