For centuries, Saturn\u2019s shimmering rings have captivated astronomers and stargazers alike. Yet their ages and the histories of Saturn\u2019s moons have remained among planetary science\u2019s most tantalizing mysteries.<\/p>\n
Saturn\u2019s system<\/a> is mainly shaped by Titan, its largest moon, which is moving outward rapidly due to tidal forces within Saturn<\/a>.<\/p>\n A new study led by SETI Institute scientist Matija \u0106uk suggests that Saturn\u2019s moons and rings<\/a> may be linked, with Titan possibly formed from a merger of two moons.<\/p>\n Near the end of its mission, Cassini measured Saturn\u2019s internal mass distribution, which governs the planet\u2019s spin-axis wobble (precession). Scientists had long believed Saturn\u2019s precession matched Neptune\u2019s, allowing gravitational interactions to tilt Saturn and reveal its rings. But Cassini showed Saturn\u2019s mass is more concentrated at its center, breaking that resonance.<\/p>\n Scientists Detected Unexpected Behavior on Saturn\u2019s Moon Titan<\/a><\/p>\n To explain this, researchers at MIT and UC Berkeley proposed that Saturn once had an extra moon, which was destabilized and either ejected or destroyed. \u0106uk\u2019s team took this idea further.<\/p>\n Computer simulations suggest the extra moon likely collided with Titan. This merger would have erased Titan\u2019s craters, disturbed its orbit, and left behind debris. Saturn\u2019s small, chaotic moon Hyperion, locked in resonance with Titan, may itself be a remnant of this upheaval.<\/p>\n SETI Institute scientist Matija \u0106uk, who led the study, said<\/a>, \u201cIn simulations where the extra moon became unstable, Hyperion was often lost and survived only in rare cases. We recognized that the Titan-Hyperion lock is relatively young, only a few hundred million years old.\u201d<\/p>\n \u201cPerhaps Hyperion did not survive this upheaval but resulted from it. If the extra moon merged with Titan<\/a>, it would likely produce fragments near Titan\u2019s orbit. That is exactly where Hyperion would have formed.\u201d<\/p>\n The simulations also suggest that Saturn\u2019s largest moon, Titan, resulted from the merger of two earlier moons: a \u201cProto-Titan,\u201d nearly as large as Titan itself, and a smaller \u201cProto-Hyperion.\u201d This merger would have erased Titan\u2019s craters, disturbed its orbit, and left behind debris.<\/p>\n Titan\u2019s orbit is still settling down, which hints at a recent collision with a smaller moon, Proto\u2011Hyperion. Before the merger, Proto\u2011Titan may have looked like Jupiter\u2019s Callisto, cratered and without an atmosphere. The study also found that Proto\u2011Hyperion tilted the orbit of Saturn\u2019s distant moon Iapetus before it disappeared, solving another mystery.<\/p>\n If a moon\u2011moon merger created Titan, then Saturn\u2019s rings likely came from a different event. Researchers suggest the rings formed from collisions between medium\u2011sized moons closer to Saturn.<\/p>\n Computer simulations supported the idea- showing that most of the debris from these crashes would clump back into new moons, but some fragments would drift inward and spread out to form Saturn\u2019s bright rings<\/a>.<\/p>\n Mars once had a ring billions of years ago<\/a><\/p>\n For a long time, scientists thought Saturn\u2019s inner moons<\/a> collided because of the Sun\u2019s influence. But new research shows the real trigger was Titan\u2019s earlier merger. After that event, Titan\u2019s orbit became stretched (eccentric), and this can throw smaller moons off balance when their orbits line up with Titan\u2019s in a pattern called orbital resonance.<\/p>\n When this happens, the smaller moons\u2019 paths become unstable, stretching out until they crash into each other. These collisions made debris. Some of it re-formed into moons, while the rest drifted inward to form Saturn\u2019s rings. We do not know exactly when this second cataclysm happened, but it took place after Titan merged. This timing fits with the idea that Saturn\u2019s rings are about 100 million years old<\/a>.<\/p>\n Journal Reference:<\/p>\n