In May 2012, the "Dawn" team published preliminary results of their study of Vesta, including estimates of the size of Vesta's metal-rich core, which is theorized to be across. The scientists stated that they think that Vesta is the "last of its kind" – the only remaining example of the large planetoids that came together to form the rocky planets during the formation of the Solar System. In October 2012, further "Dawn" results were published, on the origin of anomalous dark spots and streaks on Vesta's surface, which were likely deposited by ancient asteroid impacts. In December 2012, it was reported that "Dawn" had observed gullies on the surface of Vesta that were interpreted to have been eroded by transiently flowing liquid water. More details about the "Dawn" mission's scientific discoveries at Vesta are included on the Vesta page.