Starship Asterisk*

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Four hundred years ago, the astronomer Galileo Galilei announced his discovery of four moons orbiting around the planet Jupiter, each seen as a distinct white dot through his telescope. However, only in the span of the last four decades have astronomers been able to study the Jovian moons in detail to reveal that the four—Io, Europa, Ganymede, and Callisto—are fascinating worlds of their own.

Though they are all of similar sizes—about one fourth of Earth's radius—the four moons are diverse: Io is violently volcanic, Europa is encrusted in ice, Ganymede has a magnetic field, and Callisto is pockmarked with ancient craters. Moreover, icy Europa is considered a strong candidate for hosting life in the solar system.

One open question still puzzles planetary scientists: How did the Jovian satellites form?

Now, Caltech professor of planetary science Konstantin Batygin and his collaborator Alessandro Morbidelli of Observatoire de la Côte d'Azur in France have proposed an answer to this longstanding question. Using analytical calculations and large-scale computer simulations, they propose a new theory of the Jovian satellites' origins. ...

• Astrophysical Journal 894(2):143 (2020 May 10) DOI: 10.3847/1538-4357/ab8937
• arXiv.org > astro-ph > arXiv:2005.08330 > 17 May 2020