One of the most bizarre phenomena in our Solar System is the strange way that Uranus spins on its side. That’s a puzzle because all the other planets spin upright. What could have happened to make Uranus so different, particularly from its neighbor Neptune, which formed at the same time in similar circumstances?
The conventional thinking holds that soon after the Solar System formed, Uranus was knocked on its side by a series of collisions with some of the numerous planetesimals that swept through the region at that time.
The problem with this theory is that Neptune survived the same conditions unscathed. This suggests some other process was responsible for Uranus’ bizarre behavior. But what could this be?
Now we get an answer thanks to the work of Melaine Saillenfest at the Paris Observatory in France, and colleagues, who think that Uranus could have become tilted on its side in ...
