A Study of Jupiter and Its Four Moons %

Astronomer Galileo Galilei observed four moons orbiting around Jupiter some 400 years ago. But it is only in the last four decades that astronomers have been able to study the four moons and reveal their mechanisms of orbit. The four moons (lo, Europa, Ganymede and Callisto) are one fourth of the Earth’s radius in size; however, they all have different properties. Lo has been found to be violently volcanic, Europa is covered in ice, Ganymede has a magnetic field while Callisto is marked with ancient craters. In terms of hosting life in the solar system, astronomers consider Europa as a strong candidate.

Professor Konstantin Batygin and Alessandro Morbidelli have been able to provide an explanation for the formation and orbiting patterns of these moons. In the first few million years of our sun’s lifetime, it was surrounded by a protoplanetary disk- a rotating circumstellar disk of dense gas and dust surrounding the young newly formed star. Jupiter originated from this disk and since it was a newly formed planet, it became encircled by its own disk of dust and dense gas. Considering the physics of interactions between dust and gas in the Circum-Jovian disk, the researchers demonstrated that for the icy grains, the force dragging them towards Jupiter and the force carrying them in the outward flow of the gas cancel each other perfectly due to which the disk acts like a giant dust trap.

Due to this balance between inward drag and outward flow of gas, the disk around Jupiter became rich in icy dust grains. Over time, the ring of dust increased in size and collapsed under its own weight into thousands of icy asteroid-like objects over a distance of 100 Km. Over thousands of years, these asteroid-like objects formed into Jupiter’s moons one at a time. This sequential process of formation of the moons led to an orbital resonance; every 4 times Lo orbits around Jupiter, Europa orbits it twice while Ganymede only goes around once. This pattern of orbit is the most striking and distinguishing feature of the moons’ orbit. These findings are significant as they can be used by astronomers and researchers in the future to study and understand the orbit patterns of the moons of other planets in our solar system.