No, I don’t mean Matthew McConaughey. Our first interstellar visitor is a small, quarter-mile diameter rock that recently flew nearby Earth, and is now leaving our solar system for the constellation Pegasus. The object, temporarily named A/2017 U1, was first detected by postdoctoral researcher Dr. Rob Weryk at the University of Hawaii when he realized its trajectory could not be a normal asteroid or comet orbit in solar system. He observed the alien rock coming roughly from the constellation of Lyra on a trajectory that is almost perpendicular to the orbits of most objects in our solar system.
While never previously observed, these types of interstellar objects have long been expected to exist. They are predicted as a by-product of planet formation: planets orbiting a star form by consuming material left over from the surrounding halo of matter that initially fed the growing star. However, this process is rather inefficient and instead of incorporating all the available material, some is ejected from the solar system. This ejected material escapes the star’s gravity and streams out into interstellar space until encountering another solar system and, hopefully, is detected.
Dr. Matthew Holman, the Director of the Minor Planet Center (MPC), says that “by carefully determining how frequently the material ejected from other solar systems is passing through our own, we can understand the processes and frequency of planet formation in other solar systems in our neighborhood.” While a lot more data needs to be taken on these interstellar wanderers, it is the seminal event scientists have been waiting decades for to study planet formation.
Thank you to Dr. Matthew Holman, the Directory of the Minor Plant Center (MPC) at the Center for Astrophysics (CFA) at Harvard University, for his explanation on the research implications of studying these interstellar objects.