Free Astronomy Magazine September-October 2018

SEPTEMBER-OCTOBER 2018 came unevenly distributed outside the nu- cleus of Uranus. The icy component spread more evenly in the outer part of the mantle of the giant planet, where it formed an ice shell with properties perhaps different from those of the pre-existing ice. About this, what the authors of the study say in the sci- A bove, a frame of a simulation by the Kegerreis team. In this stage of the collision between the two planets, Uranus has almost com- pletely engulfed the intruder. The nucleus of the lat- ter, similar to an umbilical cord, is falling towards the Uranus nucleus. The brightness is proportional to the developed energy. [ApJ, J. Kegerreis et al.] The video on the side shows the dy- namics of the dou- ble grazing colli- sion. [J. Kegerreis/ Durham University] T he parameters relevant for setting up an im- pact simulation: the x and y positions of the impactor, its initial velocity, vx, and the masses of the proto-Uranus target (t) and the impactor (i). The results of the new study essentially con- firm those obtained by the team of Slattery, especially with regard to the mass of the adapter, undoubtedly close to twice that of the Earth. Additionally, the Kegerreis team has shown how and where the mass and en- ergy conferred by the unknown planet may have settled inside the young Uranus. Among all the combina- tions of the variables con- sidered, some final scenar- ios effectively represent what we see in reality. Most likely the collision was grazing, with the impactor having penetrated the frozen mantle of the young Uranus, fragmenting and dissolving the icy masses in- volved in the event. Up to 40% of the rock com- ponent of the projectile be-