Free Astronomy Magazine September-October 2018

25 SEPTEMBER-OCTOBER 2018 PLANETOLOGY In addition to the inclination of the rotation axis, it was also possible to represent within approximation the inhomogeneities of the internal structure that resulted from the mass carried by the impactor, and thus to give an answer to the question of the anom- alous positioning of the magnetic field. A cataclysmic event of that magnitude could not occur without some record among the large array of moons (not less than 27) that surround the planet: the material flung into orbit by the impact may have contributed to generating many of them. It is obvious that understanding the exact dynamics of the event would add relevant information to the general picture of the planetary system evo- lution as a whole. Nevertheless, after the work of the Slattery team, it took 26 years to see another group of researchers return to the simulation of Uranus and develop a bet- ter model. The first author of the new work is Jacob A. Kegerreis, of the Institute for Com- putational Cosmology of Durham University, UK. The results of the simulations appeared in the July issue of The Astrophysical Journal . Being able to count on (obviously) superior modern computing power, Kegerreis and colleagues started a series of simulations that included over fifty different scenarios of an impact between a young Uranus and an unknown planet in our early solar system. By including around one million virtual par- ticles, the new simulations succeeded in rep- resenting with good resolution the distri- bution of the rocky, icy and gaseous compo- nents before, during and after the impact. T his false-color image, created by Erich Karko- schka, processing data produced 20 years ago by Hub- ble’s Near Infrared Camera and Multi- Object Spectrome- ter, shows numer- ous clouds (some of which are rela- tively warm), the ring system and 10 of the 27 moons orbiting around the planet. [NASA/JPL/STScI]